/* ============================================================
   GEN CHEM INTERACTIVES — COMPONENTS
   The shared component library. Every lesson inherits these.
   Lesson-specific styling should be rare; prefer extending here.
   ============================================================ */

/* ---- utilities ---- */
/* Wrap a chemical formula (e.g. "CO<sub>2</sub>") in .formula anywhere it sits
   inside a flex/grid ancestor, so the subscript can't be torn onto its own line. */
.formula{white-space:nowrap;}

/* ---- section shells ---- */
section{position:relative;z-index:2;padding:var(--beat) var(--gutter);}
.wrap{max-width:78rem;margin:0 auto;width:100%;}
.narrow{max-width:var(--prose);margin:0 auto;}
.section-tag{display:flex;align-items:baseline;gap:.9rem;margin-bottom:1.5rem;}
.section-tag .num{font-family:var(--mono);font-size:.74rem;font-weight:600;letter-spacing:.12em;color:var(--accent);border:1px solid var(--accent-soft);padding:.18rem .55rem;}

/* ---- topbar + table of contents ---- */
.topbar{position:fixed;top:0;left:0;right:0;z-index:60;display:flex;align-items:center;justify-content:space-between;
  padding:.6rem var(--gutter);background:color-mix(in srgb,var(--paper) 88%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--hair-soft);}
.topbar-left{display:flex;align-items:center;gap:.75rem;flex-shrink:0;}
.crumb{font-family:var(--mono);font-size:.68rem;letter-spacing:.13em;text-transform:uppercase;color:var(--ink-mute);white-space:nowrap;}
.crumb b{color:var(--ink);font-weight:600;}
.toc-btn,.theme-toggle,.topbar-home-btn,.clear-progress-btn,.contact-feedback-btn{height:34px;border:1px solid var(--hair);background:var(--card);color:var(--ink-mute);cursor:pointer;transition:all .2s ease;display:inline-flex;align-items:center;justify-content:center;text-decoration:none;box-sizing:border-box;border-radius:4px;white-space:nowrap;flex-shrink:0;}
.toc-btn,.topbar-home-btn,.clear-progress-btn,.contact-feedback-btn{padding:0 .7rem;gap:.45rem;font-family:var(--mono);font-size:.66rem;letter-spacing:.12em;text-transform:uppercase;white-space:nowrap;}
.toc-btn:hover,.theme-toggle:hover,.topbar-home-btn:hover,.clear-progress-btn:hover,.contact-feedback-btn:hover{color:var(--accent);border-color:var(--accent);background:var(--paper-2);}
.toc-btn svg,.topbar-home-btn svg,.clear-progress-btn svg,.contact-feedback-btn svg{width:13px;height:13px;flex-shrink:0;}
.theme-toggle{width:34px;flex-shrink:0;}
.theme-toggle svg{width:16px;height:16px;flex-shrink:0;}
.theme-toggle .sun{display:none;} :root.dark .theme-toggle .moon{display:none;} :root.dark .theme-toggle .sun{display:block;}
.topbar-right{display:flex;align-items:center;gap:.5rem;flex-shrink:0;}
.toc-drop{position:fixed;top:52px;left:var(--gutter);z-index:59;background:var(--card);border:1px solid var(--hair);min-width:260px;
  box-shadow:0 12px 40px rgba(0,0,0,.14);opacity:0;visibility:hidden;transform:translateY(-8px);transition:all .2s ease;}
.toc-drop.open{opacity:1;visibility:visible;transform:none;}
.toc-drop a{display:flex;gap:.7rem;align-items:baseline;padding:.6rem .9rem;text-decoration:none;color:var(--ink-soft);font-family:var(--display);font-size:.92rem;font-weight:500;border-bottom:1px solid var(--hair-soft);transition:background .15s ease,color .15s ease;}
.toc-drop a:last-child{border-bottom:none;}
.toc-drop a:hover{background:var(--paper-2);color:var(--accent);}
.toc-drop a .tnum{font-family:var(--mono);font-size:.66rem;color:var(--ink-mute);min-width:1.4rem;}

@media (max-width: 768px) {
  .topbar-left { gap: .4rem; }
  .topbar-right { gap: .35rem; }
  #ptableBtn .topbar-btn-label,
  .print-btn .topbar-btn-label,
  .contact-feedback-btn .topbar-btn-label {
    display: none;
  }
  #ptableBtn, .print-btn, .contact-feedback-btn, .topbar-home-btn {
    padding: 0 0.5rem;
  }
}

@media (max-width: 600px) {
  .crumb { display: none; }
  .topbar { padding: .5rem .75rem; }
  .toc-drop { left: .75rem; right: .75rem; min-width: auto; }
}

/* ---- reveal on scroll ---- */
.reveal{opacity:0;transform:translateY(18px);transition:opacity .6s cubic-bezier(.22,1,.36,1),transform .6s cubic-bezier(.22,1,.36,1);}
.reveal.in{opacity:1;transform:none;}
@media(prefers-reduced-motion:reduce){.reveal{opacity:1!important;transform:none!important;}}

/* ---- hero + meta strip ---- */
.hero{min-height:94vh;display:flex;flex-direction:column;justify-content:center;padding-top:5rem;}
.hero h1{margin:.7rem 0 1.5rem;max-width:17ch;}
.hero h1 .flip{color:var(--accent);}
.meta-strip{display:grid;grid-template-columns:1fr;gap:1.6rem;margin-top:2.75rem;max-width:62rem;}
@media(min-width:760px){.meta-strip{grid-template-columns:repeat(3,1fr);column-gap:2rem;}}
.meta-block{border-top:2px solid var(--ink);padding-top:.6rem;}
.meta-block .k{font-family:var(--mono);font-size:.68rem;letter-spacing:.14em;text-transform:uppercase;color:var(--ink-mute);margin-bottom:.4rem;}
.meta-block .v{font-family:var(--serif);font-size:1rem;line-height:1.45;color:var(--ink-soft);}
.meta-block .v b{font-family:var(--display);font-weight:700;color:var(--ink);font-size:1.15rem;display:block;margin-bottom:.25rem;}

/* ---- next-section button ---- */
.next-cue{display:flex;justify-content:center;margin-top:var(--beat);}
.next-btn{font-family:var(--mono);font-size:.7rem;letter-spacing:.18em;text-transform:uppercase;color:var(--ink-mute);background:var(--card);border:1px solid var(--hair);
  padding:.7rem 1.3rem;cursor:pointer;display:inline-flex;align-items:center;gap:.6rem;transition:all .2s ease;min-height:44px;box-shadow:0 2px 8px rgba(0,0,0,.04);}
.next-btn:hover{color:var(--accent);border-color:var(--accent);}
.next-btn .chev{transition:transform .2s ease;}
.next-btn:hover .chev{transform:translateY(2px);}

/* ---- prose helpers ---- */
.step+.step{margin-top:1.15rem;}
.step.bullet{display:flex;gap:.85rem;align-items:baseline;color:var(--ink-soft);}
.step.bullet::before{content:'';flex:0 0 8px;height:8px;background:var(--accent);margin-top:.55em;}
.step.bullet p{max-width:none;}
.levers{display:grid;grid-template-columns:1fr;gap:1rem;margin-top:1.85rem;}
@media(min-width:720px){.levers{grid-template-columns:1fr 1fr;}}
.lever{background:var(--card);border:1px solid var(--hair);padding:1.5rem 1.6rem;}
.lever .arrow{font-family:var(--mono);font-size:1.5rem;color:var(--accent);font-weight:600;}
.lever h4{margin:.45rem 0 .65rem;}
.lever p{font-size:1rem;color:var(--ink-soft);max-width:none;}
.callout{border-left:3px solid var(--accent);background:var(--card);padding:1.2rem 1.5rem;margin:1.6rem 0;}
.callout .label{margin-bottom:.55rem;}
.callout p{font-family:var(--serif);font-style:italic;font-size:1.12rem;max-width:none;}

strong.term{font-weight:700;color:var(--ink);border-bottom:1.5px dashed var(--accent-soft);padding-bottom:1px;}

/* ---- expandable dense block ---- */
.more-wrap{margin-top:1rem;}
.more-toggle{font-family:var(--mono);font-size:.7rem;letter-spacing:.1em;text-transform:uppercase;color:var(--accent);background:transparent;border:none;border-bottom:1px solid var(--accent-soft);cursor:pointer;padding:.2rem 0;}
.more-body{max-height:0;overflow:hidden;opacity:0;transition:max-height .5s ease,opacity .4s ease;}
.more-body.open{max-height:600px;opacity:1;margin-top:1rem;}

/* ============ SHARED INTERACTIVE FRAME ============
   Every interactive — Bohr builder, trend explorer, BCA table,
   equation balancer, graph — lives in this same frame.
   .interactive  → bordered card
   .interactive-head → mono label (+ optional tabs)
   .readout → result/explanation panel
   ================================================== */
.interactive{background:var(--card);border:1px solid var(--hair);padding:clamp(1.1rem,3vw,2rem);margin-top:1.6rem;}
.interactive-head{display:flex;align-items:baseline;justify-content:space-between;gap:1rem;flex-wrap:wrap;margin-bottom:1.25rem;}
.interactive-head .label{color:var(--accent);}
.tabs{display:flex;flex-wrap:wrap;gap:.5rem;}
.tab{font-family:var(--mono);font-size:.73rem;letter-spacing:.05em;text-transform:uppercase;padding:.58rem .9rem;background:transparent;color:var(--ink-soft);border:1px solid var(--hair);cursor:pointer;transition:all .18s ease;min-height:42px;}
.tab:hover{border-color:var(--accent);color:var(--accent);}
.tab.active{background:var(--ink);color:var(--paper);border-color:var(--ink);}
.readout{border:1px solid var(--hair);background:var(--paper);padding:1.25rem 1.4rem;}
.readout .label{margin-bottom:.6rem;}
.readout h4{color:var(--accent);margin-bottom:.5rem;}
.readout p{font-size:.98rem;color:var(--ink-soft);max-width:none;}
.readout .dirs{display:flex;gap:1.4rem;margin-top:.9rem;flex-wrap:wrap;}
.readout .dir{font-family:var(--mono);font-size:.74rem;color:var(--ink);}
.readout .dir span{color:var(--accent);font-weight:600;}

/* ---- atom / Bohr diagram (reusable atomic-level component) ---- */
.atom-stage{display:grid;grid-template-columns:1fr;gap:1.3rem;align-items:center;}
@media(min-width:820px){.atom-stage{grid-template-columns:1fr 1fr;}}
.atom-svg-wrap{display:flex;flex-direction:column;align-items:center;width:100%;}
.atom-shell{fill:none;stroke:var(--shell);stroke-width:1;}
.atom-nucleus{fill:var(--nucleus);}
.atom-nuc-label{fill:#fff;font-family:var(--mono);font-weight:600;}
.atom-e{fill:var(--electron);}
.atom-controls{display:flex;align-items:center;gap:.8rem;margin-top:1rem;}
.step-btn{width:42px;height:42px;border:1px solid var(--hair);background:var(--card);color:var(--ink);font-family:var(--display);font-size:1.2rem;font-weight:700;cursor:pointer;transition:all .18s ease;}
.step-btn:hover:not(:disabled){border-color:var(--accent);color:var(--accent);}
.step-btn:disabled{opacity:.3;cursor:not-allowed;}
.step-readout-el{font-family:var(--display);font-weight:700;font-size:1.05rem;min-width:8.5rem;text-align:center;}
.step-readout-el span{font-family:var(--mono);font-weight:500;font-size:.74rem;color:var(--ink-mute);display:block;text-transform:uppercase;letter-spacing:.1em;margin-top:.15rem;}
.atom-stats{display:flex;gap:1.5rem;margin-top:.6rem;font-family:var(--mono);font-size:.78rem;color:var(--ink-soft);}
.atom-stats b{color:var(--accent);}

/* ---- periodic table heat-map (reusable component) ---- */
.ptable-scroll{overflow-x:auto;padding-bottom:.5rem;}
.ptable{display:grid;grid-template-columns:repeat(2,1fr) .45fr repeat(6,1fr);gap:4px;min-width:520px;}
.pcell{aspect-ratio:1/1;border:1px solid var(--hair-soft);position:relative;display:flex;flex-direction:column;align-items:center;justify-content:center;background:var(--card);transition:background .35s ease,transform .12s ease;color:var(--ink);user-select:none;overflow:hidden;}
.pcell.has-data{cursor:pointer;}
.pcell.has-data:hover{transform:scale(1.1);z-index:5;border-color:var(--ink);}
.pcell .sym{font-family:var(--display);font-weight:800;font-size:clamp(.72rem,1.8vw,1.05rem);line-height:1;}
.pcell .z{font-family:var(--mono);font-size:.54rem;position:absolute;top:2px;left:3px;opacity:.7;}
.pcell .val{font-family:var(--mono);font-weight:500;font-size:clamp(.56rem,1.3vw,.7rem);opacity:.95;margin-top:2px;}
.pcell.spacer{visibility:hidden;}
.pcell.dim{opacity:.3;}
.pcell.selected{outline:2px solid var(--accent);outline-offset:-2px;z-index:4;}
.legend{display:flex;align-items:center;justify-content:center;gap:1.5rem;margin-top:1.2rem;font-family:var(--mono);font-size:.66rem;letter-spacing:.07em;text-transform:uppercase;color:var(--ink-mute);flex-wrap:wrap;}
.legend .bar{height:11px;width:130px;border:1px solid var(--hair);}
.legend .swatch{display:inline-flex;align-items:center;gap:.5rem;}
.legend .chip{width:13px;height:13px;min-height:0;padding:0;display:inline-block;flex-shrink:0;border:1px solid var(--hair);cursor:default;}
.explorer-grid{display:grid;grid-template-columns:1fr;gap:1.25rem;margin-top:1.5rem;}
@media(min-width:860px){.explorer-grid{grid-template-columns:1.25fr 1fr;align-items:start;}}
.cmp-hint{font-family:var(--mono);font-size:.7rem;color:var(--ink-mute);}
.cmp-out{margin-top:.75rem;font-family:var(--serif);font-style:italic;font-size:1.02rem;color:var(--ink);min-height:1.5em;}
.cmp-out b{font-style:normal;font-family:var(--display);font-weight:700;color:var(--accent);}

/* ============ RETRIEVAL WIDGETS ============ */
/* predict-then-reveal */
.predict-q{border-left:2px solid var(--accent);padding-left:1.25rem;margin:1rem 0 1.4rem;}
.predict-q p{font-family:var(--serif);font-style:italic;font-size:clamp(1.15rem,2.3vw,1.55rem);color:var(--ink);max-width:none;}
.options{display:grid;grid-template-columns:1fr;gap:.65rem;}
@media(min-width:640px){.options.cols{grid-template-columns:1fr 1fr;}}
.opt{text-align:left;padding:.95rem 1.15rem;background:var(--card);border:1px solid var(--hair);cursor:pointer;font-family:var(--display);font-weight:500;font-size:1rem;color:var(--ink);transition:all .18s ease;min-height:48px;}
.opt:hover{border-color:var(--accent);}
.opt .ltr{display:block;font-family:var(--mono);font-size:.62rem;letter-spacing:.14em;color:var(--ink-mute);margin-bottom:.3rem;}
.opt.correct{border-color:var(--good);border-width:2px;background:color-mix(in srgb,var(--good) 12%,transparent);}
.opt.wrong{border-color:var(--accent);background:color-mix(in srgb,var(--accent) 10%,transparent);opacity:.8;}
.reveal-box{max-height:0;overflow:hidden;opacity:0;transition:max-height .55s ease,opacity .4s ease;}
.reveal-box.show{max-height:800px;opacity:1;margin-top:1.3rem;}
.reveal-card{background:var(--card);border-left:3px solid var(--good);padding:1.2rem 1.5rem;}
.reveal-card .label{color:var(--good);margin-bottom:.55rem;}
.reveal-card p{max-width:none;} .reveal-card p+p{margin-top:.7rem;}

/* fill-in-the-blank recall */
.recall-section{background:var(--paper-2);border-top:1px solid var(--hair-soft);border-bottom:1px solid var(--hair-soft);}
.recall-sentence{font-family:var(--serif);font-size:clamp(1.2rem,2.5vw,1.75rem);line-height:1.95;color:var(--ink);margin:1.3rem 0;max-width:52rem;}
.blank{display:inline-block;min-width:7rem;border:none;border-bottom:2px solid var(--accent);background:transparent;font-family:var(--serif);font-size:inherit;color:var(--accent);font-style:italic;text-align:center;padding:0 .35rem;outline:none;transition:all .25s ease;}
.blank:focus{background:color-mix(in srgb,var(--accent) 9%,transparent);}
.blank.correct{color:var(--good);border-color:var(--good);} .blank.wrong{color:var(--accent);border-color:var(--accent);} .blank.shown{border-style:dashed;opacity:.9;}
.actions{display:flex;gap:.6rem;align-items:center;flex-wrap:wrap;margin-top:1.5rem;}
.btn{font-family:var(--mono);font-size:.72rem;letter-spacing:.12em;text-transform:uppercase;padding:.72rem 1.15rem;background:var(--ink);color:var(--paper);border:1px solid var(--ink);cursor:pointer;transition:all .18s ease;min-height:44px;}
.btn:hover{background:var(--accent);border-color:var(--accent);}
.btn.ghost{background:transparent;color:var(--ink-soft);border-color:var(--hair);} .btn.ghost:hover{color:var(--accent);border-color:var(--accent);background:transparent;}
.feedback{font-family:var(--mono);font-size:.74rem;color:var(--ink-mute);min-height:1.2em;} .feedback.good{color:var(--good);} .feedback.accent{color:var(--accent);}

/* self-explain */
.selfx-mark{border-left:2px solid var(--accent);padding-left:1.25rem;margin:1rem 0 .6rem;}
.selfx-mark p{font-family:var(--serif);font-style:italic;font-size:clamp(1.2rem,2.4vw,1.6rem);color:var(--ink);max-width:none;}
.hint{font-family:var(--display);font-size:.95rem;color:var(--ink-soft);margin-bottom:1rem;}
.textbox{width:100%;max-width:48rem;padding:.95rem 1.15rem;background:var(--card);border:1px solid var(--hair);font-family:var(--serif);font-size:1.05rem;line-height:1.6;color:var(--ink);resize:vertical;min-height:110px;outline:none;transition:border-color .2s ease;}
.textbox:focus{border-color:var(--accent);}
.peek-box{max-height:0;overflow:hidden;opacity:0;transition:max-height .5s ease,opacity .4s ease;} .peek-box.show{max-height:600px;opacity:1;margin-top:1rem;}

/* exam practice + mark scheme */
.exam-frame{border:1px solid var(--hair);background:var(--card);padding:clamp(1.2rem,3vw,2rem);margin-top:1.4rem;}
.exam-meta{display:flex;justify-content:space-between;gap:1rem;flex-wrap:wrap;align-items:baseline;margin-bottom:1rem;}
.exam-src{font-family:var(--mono);font-size:.68rem;letter-spacing:.12em;text-transform:uppercase;color:var(--ink-mute);}
.exam-marks{font-family:var(--mono);font-size:.68rem;letter-spacing:.12em;text-transform:uppercase;color:var(--accent);border:1px solid var(--accent-soft);padding:.15rem .5rem;}
.exam-q{font-family:var(--serif);font-size:clamp(1.15rem,2.3vw,1.5rem);line-height:1.4;color:var(--ink);max-width:none;}
.exam-q .sub{display:block;font-family:var(--display);font-size:.98rem;color:var(--ink-soft);margin-top:.6rem;font-weight:400;}
.scheme{max-height:0;overflow:hidden;opacity:0;transition:max-height .6s ease,opacity .45s ease;} .scheme.show{max-height:1100px;opacity:1;margin-top:1.3rem;}
.scheme-card{border-left:3px solid var(--good);background:var(--paper);padding:1.2rem 1.5rem;}
.scheme-card .label{color:var(--good);margin-bottom:.75rem;}
.pts{list-style:none;} .pts li{display:flex;gap:.7rem;align-items:baseline;color:var(--ink-soft);font-size:1rem;line-height:1.5;margin-bottom:.6rem;}
.pts li::before{content:'+1';font-family:var(--mono);font-size:.68rem;color:var(--good);font-weight:600;flex:0 0 auto;border:1px solid var(--good-soft);padding:0 .25rem;}
.pts li.cap::before{content:'\2691';border:none;color:var(--accent);font-size:1.15rem;font-family:var(--display);font-weight:700;line-height:0.8;padding:0;}

/* ---- footer ---- */
.footer{text-align:center;padding:2.75rem var(--gutter) 3.5rem;border-top:1px solid var(--hair-soft);background:var(--paper-3);}
.footer .label{color:var(--ink-mute);} .footer p{font-family:var(--serif);font-style:italic;color:var(--ink-soft);max-width:none;margin-top:.5rem;}

/* ============ PARTICLE-DIAGRAM CONVENTIONS ============
   Adheres to the class poster set. Reuse these classes for any
   particle / container / energy diagram so they stay consistent.
   particle = filled circle (.d-particle) ; metal = square (.d-metal)
   framing  = dashed box (.d-frame) ; container = solid walls (.d-wall)
   water    = blue wavy line (.d-water)
   motion   = brackets(solid) / lumps(liquid) / tails(gas) drawn per-lesson
   ALWAYS include a legend; ALWAYS conserve particles before/after.
   ====================================================== */
.diagram{margin:1.5rem 0;}
.diagram svg,.diagram img{width:100%;height:auto;display:block;}
.diagram-cap{font-family:var(--mono);font-size:.66rem;letter-spacing:.1em;text-transform:uppercase;color:var(--ink-mute);text-align:center;margin-top:.7rem;}

/* ---- figure system: one primitive for all figure widths (TODO.md §1.1) ----
   Width comes from a named tier tied to the prose column, never a raw pixel value.
   --full/--wide figures must sit outside .narrow (or bleed out of it) or the
   .narrow max-width silently caps them back down to the prose column. */
.figure{margin:1.75rem auto;}
.figure--sm{max-width:var(--fig-sm);}
.figure--md{max-width:var(--fig-md);}
.figure--full{max-width:var(--fig-full);}
.figure--wide{max-width:var(--fig-wide);}
.figure svg,.figure img{width:100%;height:auto;display:block;}
.d-particle{fill:var(--electron);stroke:var(--ink);stroke-width:1.2;}
/* SVG geometry attributes cannot take var() — a circle written as
   r="var(--dia-r-*)" fails attribute parsing and collapses to r=0
   (invisible). The CSS `r` property DOES accept var(), and CSS wins
   over the presentation attribute, so re-apply the radius here.
   Tokens are unitless; in SVG, 1px = 1 user unit. */
circle[r="var(--dia-r-particle)"]{r:calc(var(--dia-r-particle) * 1px);}
circle[r="var(--dia-r-atom-sm)"]{r:calc(var(--dia-r-atom-sm) * 1px);}
circle[r="var(--dia-r-atom)"]{r:calc(var(--dia-r-atom) * 1px);}
.d-metal{fill:var(--ink-mute);stroke:var(--ink);stroke-width:1.2;}
.d-shell{fill:none;stroke:var(--shell);stroke-width:0.8;}
.d-nuc{fill:var(--nucleus);}
.d-nuc-t{fill:#fff;font-family:var(--mono);font-weight:600;font-size:9px;}
.d-frame{fill:none;stroke:var(--ink-mute);stroke-width:1.5;stroke-dasharray:6 4;}
.d-wall{fill:none;stroke:var(--ink);stroke-width:2.2;stroke-linecap:round;stroke-linejoin:round;}
.d-water{fill:none;stroke:var(--water);stroke-width:1.8;}
.d-arrow{stroke:var(--ink);stroke-width:1.6;}        /* NOTE: for colored arrows set stroke INLINE and omit this class (class wins over attribute) */
.d-label{font-family:var(--display);font-weight:600;fill:var(--ink);}
.d-sub{font-family:var(--mono);fill:var(--ink-mute);}

/* ---- Bohr configuration builder (reusable atomic component) ----
   Valence electrons drawn in the accent; everything else in the
   electron color, so "the ones that do chemistry" read at a glance. */
.atom-e-val{fill:var(--accent);stroke:var(--ink);stroke-width:1;}
.builder-side{display:flex;flex-direction:column;gap:1rem;}
.config-out{border:1px solid var(--hair);background:var(--paper);padding:1.1rem 1.3rem;}
.config-out .label{margin-bottom:.6rem;}
.config-shells{font-family:var(--mono);font-weight:600;font-size:clamp(1.5rem,4.5vw,2.1rem);letter-spacing:.02em;color:var(--ink);}
.config-shells .vshell{color:var(--accent);}
.config-shells .sep{color:var(--ink-mute);font-weight:400;}
.valence-pill{margin-top:.75rem;font-family:var(--mono);font-size:.76rem;letter-spacing:.04em;color:var(--ink-soft);}
.valence-pill b{color:var(--accent);font-weight:600;}
.jump-chips{display:flex;flex-wrap:wrap;gap:.4rem;}
.chip{font-family:var(--mono);font-size:.72rem;font-weight:500;padding:.4rem .65rem;background:transparent;border:1px solid var(--hair);color:var(--ink-soft);cursor:pointer;min-height:36px;transition:all .15s ease;}
.chip:hover{border-color:var(--accent);color:var(--accent);}
.chip.active{background:var(--ink);color:var(--paper);border-color:var(--ink);}

/* ---- configuration self-test (retrieval on the exact skill) ---- */
.selftest{display:grid;gap:1.25rem;}
.st-prompt{border-left:3px solid var(--accent);padding-left:1.15rem;}
.st-prompt h3{margin:.15rem 0 .25rem;}
.st-prompt .st-meta{font-family:var(--mono);font-size:.78rem;color:var(--ink-mute);}
.st-fields{display:grid;grid-template-columns:1fr;gap:1rem;}
@media(min-width:600px){.st-fields{grid-template-columns:2fr 1fr;}}
.st-fields label{font-family:var(--mono);font-size:.7rem;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-mute);display:flex;flex-direction:column;gap:.45rem;}
.st-fields input{font-family:var(--mono);font-size:1.1rem;padding:.72rem .9rem;background:var(--card);border:1px solid var(--hair);color:var(--ink);outline:none;transition:border-color .2s ease,color .2s ease;}
.st-fields input:focus{border-color:var(--accent);}
.st-fields input.correct{border-color:var(--good);color:var(--good);}
.st-fields input.wrong{border-color:var(--accent);color:var(--accent);}

/* ---- shell-filling order strip (the K→Ga wrinkle) ---- */
.fill-order{display:grid;gap:.7rem;margin:1.6rem 0;}
.fo-row{border:1px solid var(--hair);background:var(--card);padding:.85rem 1.15rem;}
.fo-head{display:flex;align-items:baseline;gap:1rem;}
.fo-el{font-family:var(--display);font-weight:700;font-size:1.05rem;min-width:6.5rem;}
.fo-cfg{font-family:var(--mono);font-size:1.05rem;color:var(--ink-soft);}
.fo-cfg b{color:var(--accent);font-weight:600;}
.fo-note{font-size:.95rem;color:var(--ink-mute);margin-top:.4rem;max-width:none;}

/* ---- diagram lightbox overlay ---- */
.diagram svg,
.diagram img {
  cursor: zoom-in;
  transition: transform 0.22s cubic-bezier(0.2, 0.8, 0.2, 1), box-shadow 0.22s ease;
}
.diagram svg:hover,
.diagram img:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 0, 0, 0.07);
}
:root.dark .diagram svg:hover,
:root.dark .diagram img:hover {
  box-shadow: 0 6px 20px rgba(255, 255, 255, 0.015);
}

/* Dark mode backing for transparent PNG/SVG images with dark text */
:root.dark .diagram img,
:root.dark .figure img,
:root.dark .d-frame img,
:root.dark .lightbox-content img,
:root.dark img.dark-backed {
  background-color: #ffffff;
  padding: 0.5rem;
  border-radius: 6px;
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.4);
}

.lightbox-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background: color-mix(in srgb, var(--paper) 95%, transparent);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  z-index: 9999;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.25s ease, visibility 0.25s;
  cursor: zoom-out;
  padding: 2.5rem;
}
:root.dark .lightbox-overlay {
  background: color-mix(in srgb, var(--paper) 92%, transparent);
}
.lightbox-overlay.open {
  opacity: 1;
  visibility: visible;
}
.lightbox-content {
  width: 100%;
  max-width: 85vw;
  max-height: 75vh;
  display: flex;
  align-items: center;
  justify-content: center;
  transform: scale(0.96);
  transition: transform 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}
.lightbox-overlay.open .lightbox-content {
  transform: scale(1);
}
.lightbox-content svg {
  width: auto;
  height: auto;
  max-width: 100%;
  max-height: 75vh;
  cursor: default;
}
.lightbox-close {
  position: absolute;
  top: 1.5rem;
  right: 1.5rem;
  width: 44px;
  height: 44px;
  border: 1px solid var(--hair);
  background: var(--card);
  color: var(--ink);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--display);
  font-size: 1.5rem;
  font-weight: 400;
  transition: all 0.2s ease;
  z-index: 10000;
}
.lightbox-close:hover {
  color: var(--accent);
  border-color: var(--accent);
  transform: rotate(90deg);
}
.lightbox-cap {
  margin-top: 1.8rem;
  font-family: var(--mono);
  font-size: 0.74rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--ink-soft);
  text-align: center;
  max-width: 680px;
  line-height: 1.4;
}

/* ============================================================
   TEXTBOOK LAYOUT & DYNAMIC COMPONENTS
   Prev/next footer navigation, tabbed dashboard, search system,
   glossary grids, and unit resource pages.
   ============================================================ */

/* ---- Textbook Footer Navigation (Injected into lessons) ---- */
.textbook-nav {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.2rem;
  padding: 2.2rem var(--gutter);
  border-top: 1px solid var(--hair);
  background: var(--paper-2);
  align-items: center;
  font-family: var(--display);
}
@media(min-width: 640px) {
  .textbook-nav {
    grid-template-columns: 1fr auto 1fr;
  }
}
.textbook-nav-link {
  display: flex;
  flex-direction: column;
  text-decoration: none;
  color: var(--ink-soft);
  transition: all 0.2s cubic-bezier(0.16, 1, 0.3, 1);
  min-height: 48px;
  justify-content: center;
  padding: 0.4rem 0.8rem;
  border-radius: 6px;
  border: 1px solid transparent;
}
.textbook-nav-link.prev {
  align-items: flex-start;
  text-align: left;
}
.textbook-nav-link.next {
  align-items: flex-end;
  text-align: right;
}
.textbook-nav-link.index {
  align-items: center;
  text-align: center;
  border: 1px solid var(--hair-soft);
  background: var(--card);
}
.textbook-nav-link:hover {
  background: var(--card);
  border-color: var(--hair-soft);
}
.textbook-nav-link.index:hover {
  border-color: var(--accent);
  background: var(--paper-3);
}
.textbook-nav-link .nav-meta {
  font-family: var(--mono);
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--ink-mute);
  margin-bottom: 0.2rem;
}
.textbook-nav-link .nav-title {
  font-size: 0.94rem;
  font-weight: 700;
  color: var(--ink);
}
.textbook-nav-link:hover .nav-meta {
  color: var(--accent);
}
.textbook-nav-link:hover .nav-title {
  color: var(--accent);
}

/* ---- Textbook Index Page Styles ---- */
.dashboard-header {
  padding: 4.5rem var(--gutter) 2rem;
  text-align: center;
  border-bottom: 1px solid var(--hair-soft);
}
.dashboard-header h1 {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 900;
  margin-bottom: 0.75rem;
  letter-spacing: -0.03em;
}
.dashboard-header .lede {
  max-width: 38rem;
  margin: 0 auto 1.5rem;
  font-size: 1.05rem;
  line-height: 1.55;
  color: var(--ink-soft);
}

/* Search bar */
.search-container {
  max-width: 32rem;
  margin: 0 auto;
  position: relative;
  width: 100%;
}
.search-input {
  width: 100%;
  height: 48px;
  padding: 0 1.25rem 0 2.8rem;
  border: 1px solid var(--hair);
  background: var(--card);
  color: var(--ink);
  font-family: var(--display);
  font-size: 0.98rem;
  border-radius: 24px;
  outline: none;
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.02);
}
.search-input:focus {
  border-color: var(--accent);
  box-shadow: 0 4px 18px var(--hair-soft), 0 0 0 3px var(--accent-soft);
}
.search-icon {
  position: absolute;
  left: 1rem;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--ink-mute);
  pointer-events: none;
}

/* Tabs */
.dashboard-tabs-wrap {
  position: sticky;
  top: 52px;
  z-index: 50;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--hair-soft);
  display: flex;
  justify-content: center;
  padding: 0.5rem var(--gutter);
}
.dashboard-tabs {
  display: flex;
  gap: 0.4rem;
  width: 100%;
  max-width: 50rem;
  overflow-x: auto;
  scrollbar-width: none; /* Hide scrollbar for Firefox */
}
.dashboard-tabs::-webkit-scrollbar {
  display: none; /* Hide scrollbar for Chrome/Safari */
}
.dashboard-tab {
  flex: 1;
  min-width: 110px;
  text-align: center;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 0.7rem 0.6rem;
  background: var(--card);
  color: var(--ink-soft);
  border: 1px solid var(--hair-soft);
  cursor: pointer;
  transition: all 0.2s ease;
  border-radius: 4px;
  white-space: nowrap;
}
.dashboard-tab:hover {
  border-color: var(--accent-soft);
  color: var(--accent);
}
.dashboard-tab.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  font-weight: 600;
}

/* Dashboard Panel Visibility */
.dashboard-panel {
  display: none;
  animation: fadeIn 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}
.dashboard-panel.active {
  display: block;
}
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: none; }
}

/* Unit Headers */
.unit-section {
  margin-top: 3rem;
  margin-bottom: 4rem;
}
.unit-section h2 {
  font-size: 1.45rem;
  font-weight: 800;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  border-bottom: 2px solid var(--ink);
  padding-bottom: 0.4rem;
  margin-bottom: 1.8rem;
  display: flex;
  justify-content: space-between;
  align-items: baseline;
}
.unit-section h2 span {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-mute);
  font-weight: 400;
  letter-spacing: 0.05em;
}

/* Lessons Grid & Cards */
.lessons-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.4rem;
}
@media(min-width: 768px) {
  .lessons-grid {
    grid-template-columns: 1fr 1fr;
  }
}
@media(min-width: 1200px) {
  .lessons-grid {
    grid-template-columns: 1fr 1fr 1fr;
  }
}
.lesson-card {
  background: var(--card);
  border: 1px solid var(--hair);
  border-radius: 6px;
  padding: 1.4rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  text-decoration: none;
  color: inherit;
  box-shadow: 0 3px 12px rgba(0, 0, 0, 0.015);
}
.lesson-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent);
  box-shadow: 0 8px 24px var(--hair-soft);
}
.lesson-card-top {
  display: flex;
  flex-direction: column;
  gap: 0.6rem;
}
.lesson-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.8rem;
}
.lesson-badge {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--accent);
  border: 1px solid var(--accent);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
  background: color-mix(in srgb, var(--accent) 6%, transparent);
}
.lesson-status-badge {
  font-family: var(--mono);
  font-size: 0.62rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.15rem 0.45rem;
  border-radius: 3px;
  font-weight: 600;
}
.lesson-status-badge.not-started {
  background: var(--paper-3);
  color: var(--ink-mute);
}
.lesson-status-badge.in-progress {
  background: color-mix(in srgb, var(--accent) 10%, transparent);
  color: var(--accent);
}
.lesson-status-badge.completed {
  background: color-mix(in srgb, var(--good) 10%, transparent);
  color: var(--good);
}
.lesson-card h3 {
  font-size: 1.08rem;
  font-weight: 800;
  line-height: 1.25;
  color: var(--ink);
}
.lesson-pes {
  font-family: var(--mono);
  font-size: 0.66rem;
  color: var(--ink-mute);
  letter-spacing: 0.05em;
}
.lesson-desc {
  font-family: var(--serif);
  font-size: 0.94rem;
  line-height: 1.45;
  color: var(--ink-soft);
  margin-top: 0.4rem;
}
.lesson-card-bottom {
  margin-top: 1.4rem;
  padding-top: 0.8rem;
  border-top: 1px solid var(--hair-soft);
}
.lesson-progress-container {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.lesson-progress-meta {
  display: flex;
  justify-content: space-between;
  font-family: var(--mono);
  font-size: 0.65rem;
  color: var(--ink-mute);
  letter-spacing: 0.05em;
}
.lesson-progress-bar-bg {
  width: 100%;
  height: 5px;
  background: var(--paper-3);
  border-radius: 3px;
  overflow: hidden;
}
.lesson-progress-bar {
  height: 100%;
  background: var(--accent);
  width: 0%;
  transition: width 0.4s ease;
  border-radius: 3px;
}
.lesson-progress-bar.completed {
  background: var(--good);
}

/* No results state */
.no-results {
  text-align: center;
  padding: 3rem 0;
  font-family: var(--serif);
  font-style: italic;
  color: var(--ink-mute);
  font-size: 1.1rem;
}

/* ---- Glossary Panel ---- */
.glossary-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1rem;
  margin-top: 2rem;
}
@media(min-width: 768px) {
  .glossary-grid {
    grid-template-columns: 1fr 1fr;
  }
}
.glossary-card {
  background: var(--card);
  border: 1px solid var(--hair-soft);
  border-radius: 6px;
  padding: 1.2rem;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 0.6rem;
  transition: all 0.2s ease;
}
.glossary-card:hover {
  border-color: var(--accent-soft);
}
.glossary-card-top {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}
.glossary-term {
  font-family: var(--display);
  font-size: 1.08rem;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: -0.01em;
}
.glossary-definition {
  font-family: var(--serif);
  font-size: 0.94rem;
  line-height: 1.5;
  color: var(--ink-soft);
}
.glossary-link {
  align-self: flex-start;
  font-family: var(--mono);
  font-size: 0.66rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-mute);
  text-decoration: none;
  border-bottom: 1px dashed var(--hair);
  padding-bottom: 1px;
  transition: all 0.15s ease;
}
.glossary-link:hover {
  color: var(--accent);
  border-color: var(--accent-soft);
}

/* ============================================================
   GLOSSARY TOOLTIP CARD
   Shared single card, repositioned by core.js on each hover/tap.
   Uses position:fixed so viewport-coord JS math stays simple.
   ============================================================ */
.gc-tooltip {
  position: fixed;
  z-index: 80;
  max-width: 280px;
  padding: .625rem .75rem;
  background: var(--card);
  border: 1px solid var(--hair);
  box-shadow: 0 4px 16px rgba(0,0,0,.13);
  opacity: 0;
  pointer-events: none;   /* never intercepts hover — tooltip is read-only */
  transition: opacity .12s ease;
}
.gc-tooltip.visible {
  opacity: 1;
}
.gc-tooltip-term {
  font-family: var(--mono);
  font-size: .75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--ink);
  margin-bottom: .4rem;
}
.gc-tooltip-def {
  font-family: var(--serif);
  font-size: .875rem;
  font-weight: 400;
  line-height: 1.5;
  color: var(--ink-soft);
}
.gc-tooltip-ex {
  font-family: var(--mono);
  font-size: .75rem;
  color: var(--ink-mute);
  margin-top: .4rem;
}
/* Downward-pointing arrow — border layer */
.gc-tooltip::before {
  content: '';
  position: absolute;
  bottom: -9px;
  left: 50%;
  transform: translateX(-50%);
  width: 0; height: 0;
  border-left: 9px solid transparent;
  border-right: 9px solid transparent;
  border-top: 9px solid var(--hair);
}
/* Downward-pointing arrow — fill layer */
.gc-tooltip::after {
  content: '';
  position: absolute;
  bottom: -8px;
  left: 50%;
  transform: translateX(-50%);
  width: 0; height: 0;
  border-left: 8px solid transparent;
  border-right: 8px solid transparent;
  border-top: 8px solid var(--card);
}

/* ---- Resources Panel ---- */
.resources-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2.2rem;
  margin-top: 2rem;
}
@media(min-width: 992px) {
  .resources-grid {
    grid-template-columns: 1fr 1fr;
  }
}
.resource-group {
  background: var(--card);
  border: 1px solid var(--hair);
  border-radius: 6px;
  padding: 1.6rem;
}
.resource-group h3 {
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--ink);
  margin-bottom: 1.2rem;
  border-bottom: 2px solid var(--accent-soft);
  padding-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.resource-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.resource-category-title {
  font-family: var(--mono);
  font-size: 0.68rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-mute);
  margin-top: 0.4rem;
  margin-bottom: 0.2rem;
  border-left: 2px solid var(--hair);
  padding-left: 0.4rem;
}
.resource-item {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.6rem 0.8rem;
  background: var(--paper-2);
  border: 1px solid var(--hair-soft);
  border-radius: 4px;
  text-decoration: none;
  color: var(--ink-soft);
  transition: all 0.18s ease;
}
.resource-item:hover {
  background: var(--paper-3);
  border-color: var(--accent-soft);
  color: var(--accent);
  transform: translateX(3px);
}
.resource-icon {
  flex-shrink: 0;
  width: 18px;
  height: 18px;
  color: var(--ink-mute);
}
.resource-item:hover .resource-icon {
  color: var(--accent);
}
.resource-title {
  font-family: var(--display);
  font-size: 0.94rem;
  font-weight: 600;
  line-height: 1.35;
}

/* ---- glossary term tooltip card ---- */
.gc-tooltip {
  position: absolute;
  z-index: 100;
  max-width: 280px;
  padding: 0.625rem 0.75rem;
  background-color: var(--card);
  border: 1px solid var(--hair);
  border-radius: 4px;
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.12s ease, visibility 0.12s ease;
  pointer-events: none;
}
:root.dark .gc-tooltip {
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.25);
}
.gc-tooltip.visible {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}
.gc-tooltip-term {
  font-family: var(--mono);
  font-weight: 700;
  font-size: 0.75rem;
  text-transform: uppercase;
  color: var(--ink);
  margin-bottom: 0.25rem;
  letter-spacing: 0.05em;
}
.gc-tooltip-definition {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 0.875rem;
  line-height: 1.5;
  color: var(--ink-soft);
}
.gc-tooltip-example {
  font-family: var(--mono);
  font-size: 0.75rem;
  color: var(--ink-mute);
  margin-top: 0.45rem;
  border-top: 1px dashed var(--hair-soft);
  padding-top: 0.35rem;
}
.gc-tooltip::after {
  content: '';
  position: absolute;
  bottom: -6px;
  left: var(--arrow-left, 50%);
  transform: translateX(-50%) rotate(45deg);
  width: 11px;
  height: 11px;
  background-color: var(--card);
  border-right: 1px solid var(--hair);
  border-bottom: 1px solid var(--hair);
  z-index: -1;
}

/* ============================================================
   WIDGET FRAMEWORK STYLES
   ============================================================ */
.widget-section {
  background: var(--card);
  border: 1px solid var(--hair);
  padding: clamp(1.1rem, 3vw, 2rem);
  margin-top: 1.6rem;
  border-radius: 4px;
}
.w-prompt {
  font-family: var(--serif);
  font-size: 1.15rem;
  line-height: 1.5;
  color: var(--ink-soft);
  margin-bottom: 1.25rem;
}
.w-prompt strong.term {
  color: var(--ink);
}
.w-controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 1.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--hair-soft);
  flex-wrap: wrap;
}
.w-feedback {
  font-family: var(--mono);
  font-size: 0.78rem;
  line-height: 1.4;
  color: var(--ink-soft);
  flex: 1 1 300px;
}
.w-feedback.correct {
  color: var(--green);
  font-weight: 600;
}
.w-feedback.wrong {
  color: var(--accent);
}
.w-buttons {
  display: flex;
  gap: 0.6rem;
}
.w-btn {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 0.6rem 1.2rem;
  min-height: 44px;
  background: var(--card);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 4px;
  transition: all 0.2s ease;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.w-btn:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--paper-2);
}
.w-btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.w-btn-check {
  background: var(--ink);
  color: var(--paper);
  border-color: var(--ink);
}
.w-btn-check:hover:not(:disabled) {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--paper);
}

/* --- Commit-Reveal: Choice --- */
.w-options-grid {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}
.w-opt {
  font-family: var(--serif);
  font-size: 1.05rem;
  text-align: left;
  padding: 0.85rem 1.2rem;
  background: var(--paper);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 4px;
  transition: all 0.18s ease;
  min-height: 44px;
  width: 100%;
}
.w-opt:hover:not(:disabled) {
  border-color: var(--accent-soft);
  background: var(--card);
}
.w-opt.selected {
  border-color: var(--accent);
  border-width: 1.5px;
  background: var(--card);
  color: var(--ink);
}
.w-opt.correct {
  border-color: var(--green) !important;
  border-width: 2px !important;
  color: var(--green) !important;
  background: color-mix(in srgb, var(--green) 6%, var(--paper)) !important;
}
.w-opt.wrong {
  border-color: var(--accent) !important;
  border-width: 2px !important;
  color: var(--accent) !important;
  background: transparent !important;
}

/* --- Commit-Reveal: Free --- */
.w-textarea {
  width: 100%;
  min-height: 120px;
  padding: 0.85rem 1rem;
  font-family: var(--serif);
  font-size: 1.05rem;
  background: var(--paper);
  border: 1px solid var(--hair);
  color: var(--ink);
  border-radius: 4px;
  resize: vertical;
  box-sizing: border-box;
}
.w-textarea:focus {
  outline: none;
  border-color: var(--accent);
}
.w-textarea:disabled {
  background: var(--paper-2);
  color: var(--ink-soft);
}
.w-progress-hint {
  font-family: var(--mono);
  font-size: 0.65rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--ink-mute);
  text-align: right;
  margin-top: 0.35rem;
  min-height: 1em;
}
.w-progress-hint.ready {
  color: var(--accent);
}
.w-reveal-area {
  margin-top: 1.25rem;
  padding: 1.25rem;
  border-left: 3px solid var(--good);
  background: var(--paper-2);
  border-radius: 0 4px 4px 0;
}
.w-reveal-area.show {
  display: block !important;
  animation: w-fadeIn 0.3s ease;
}
.w-reveal-area h4 {
  font-family: var(--display);
  color: var(--good);
  margin-top: 0;
  margin-bottom: 0.6rem;
  font-size: 0.95rem;
  letter-spacing: 0.05em;
  text-transform: uppercase;
}

/* --- Commit-Reveal: Drill --- */
.w-drill-status {
  display: flex;
  justify-content: space-between;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-mute);
  margin-bottom: 1rem;
  border-bottom: 1px dashed var(--hair-soft);
  padding-bottom: 0.5rem;
}

/* --- Faded worked example --- */
.faded-layout {
  display: flex;
  gap: 2rem;
}
.faded-panel {
  flex: 1;
  min-width: 0;
}
.faded-panel h3 {
  font-family: var(--display);
  font-size: 1.15rem;
  margin-top: 0;
  margin-bottom: 1rem;
  color: var(--ink);
  border-bottom: 1px solid var(--hair);
  padding-bottom: 0.4rem;
}
.faded-steps {
  list-style: none;
  padding: 0;
  margin: 0;
}
.faded-steps li {
  position: relative;
  padding: 0.85rem 0;
  border-bottom: 1px dashed var(--hair-soft);
}
.faded-steps li:last-child {
  border-bottom: none;
}
.faded-steps .step-label {
  display: block;
  font-family: var(--mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 0.4rem;
}
.faded-steps .step-work {
  font-family: var(--serif);
  font-size: 1.05rem;
  line-height: 1.45;
  color: var(--ink);
}
.faded-steps .step-why {
  font-family: var(--serif);
  font-size: 0.95rem;
  font-style: italic;
  color: var(--ink-soft);
  margin-top: 0.35rem;
}
.faded-model-collapsible summary {
  font-family: var(--mono);
  font-size: 0.78rem;
  text-transform: uppercase;
  color: var(--accent);
  cursor: pointer;
  padding: 0.6rem 0;
}

.w-blank-input {
  font-family: var(--mono);
  font-size: 0.95rem;
  padding: 0.3rem 0.5rem;
  border: 1px solid var(--hair);
  background: var(--paper);
  color: var(--ink);
  border-radius: 4px;
  width: 220px;
  max-width: 100%;
  box-sizing: border-box;
}
.w-blank-prompt {
  font-size: 0.85rem;
  margin-bottom: 0.4rem;
  color: var(--ink-soft);
}
.w-blank-input:focus {
  outline: none;
  border-color: var(--accent);
}
.w-blank-input.correct {
  border-color: var(--green) !important;
  color: var(--green);
  background: color-mix(in srgb, var(--green) 4%, var(--paper));
}
.w-blank-input.wrong {
  border-color: var(--accent) !important;
  background: transparent;
}
.w-blank-choices {
  display: inline-flex;
  gap: 0.35rem;
}
.w-blank-opt {
  font-family: var(--mono);
  font-size: 0.72rem;
  padding: 0.25rem 0.6rem;
  min-height: 32px;
  background: var(--paper);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 3px;
  transition: all 0.15s ease;
}
.w-blank-opt.selected {
  border-color: var(--accent);
  color: var(--ink);
}
.w-blank-opt.correct {
  border-color: var(--green) !important;
  color: var(--green) !important;
  background: color-mix(in srgb, var(--green) 6%, var(--paper)) !important;
}
.w-blank-opt.wrong {
  border-color: var(--accent) !important;
  color: var(--accent) !important;
}
.w-step-feedback {
  font-family: var(--mono);
  font-size: 0.7rem;
  margin-top: 0.35rem;
}
.w-step-feedback.correct {
  color: var(--green);
}
.w-step-feedback.wrong {
  color: var(--accent);
}
.w-step-check-btn {
  font-family: var(--mono);
  font-size: 0.65rem;
  padding: 0.2rem 0.5rem;
  background: var(--card);
  border: 1px solid var(--hair);
  cursor: pointer;
  border-radius: 3px;
  margin-left: 0.5rem;
}
.w-step-check-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

/* --- Scaffold: Bank Mode --- */
.w-bank {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  padding: 1rem;
  background: var(--paper-2);
  border: 1px dashed var(--hair);
  border-radius: 4px;
  margin-bottom: 1.5rem;
  min-height: 50px;
}
.w-card {
  font-family: var(--serif);
  font-size: 0.95rem;
  padding: 0.6rem 0.9rem;
  background: var(--card);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 4px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
  transition: all 0.15s ease;
  user-select: none;
}
.w-card:hover {
  border-color: var(--accent);
  color: var(--ink);
  transform: translateY(-1px);
}
.w-card.selected {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-soft);
  background: var(--paper-2);
}
.w-slots {
  display: flex;
  flex-direction: column;
  gap: 1rem;
  margin-bottom: 1.25rem;
}
.w-slot-row {
  display: flex;
  align-items: center;
  gap: 0.8rem;
}
.w-slot {
  flex: 1;
  min-height: 52px;
  border: 1px solid var(--hair);
  background: var(--paper);
  border-radius: 4px;
  padding: 0.4rem 0.8rem;
  display: flex;
  align-items: center;
  box-sizing: border-box;
}
.w-slot.correct {
  border-color: var(--green) !important;
  background: color-mix(in srgb, var(--green) 4%, var(--paper));
}
.w-slot.wrong {
  border-color: var(--accent) !important;
}
.w-slot-label {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-mute);
  min-width: 140px;
}
.w-chain-arrow {
  display: block;
  width: 24px;
  height: 24px;
  margin: 0.2rem auto;
}

/* --- Scaffold: Free Mode --- */
.w-scaffold-free-slot {
  margin-bottom: 1.25rem;
}
.w-scaffold-free-slot label {
  display: block;
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--accent);
  margin-bottom: 0.4rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* --- Scaffold: Table Mode --- */
.w-table-wrapper {
  overflow-x: auto;
  margin-bottom: 1.25rem;
  border: 1px solid var(--hair);
  border-radius: 4px;
}
.w-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--serif);
  font-size: 1rem;
}
.w-table th, .w-table td {
  padding: 0.75rem 1rem;
  border: 1px solid var(--hair);
  text-align: left;
}
.w-table th {
  background: var(--paper-2);
  font-family: var(--mono);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--ink-soft);
}
.w-table td {
  background: var(--card);
}

/* --- Step-Builder Mode --- */
.w-step-builder-visuals {
  margin-bottom: 1.5rem;
}

/* Mobile adjustments */
@media (max-width: 760px) {
  .faded-layout {
    flex-direction: column;
    gap: 1.5rem;
  }
  .faded-panel.faded-model {
    display: none;
  }
  .faded-model-collapsible {
    display: block;
    background: var(--paper-2);
    border: 1px solid var(--hair);
    padding: 0.5rem 1rem;
    margin-bottom: 1rem;
    border-radius: 4px;
  }
  .faded-model-collapsible[open] .faded-panel.faded-model {
    display: block;
  }
}

@keyframes w-fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: none; }
}

/* ============================================================
   MOTION PRIMITIVES STYLES
   ============================================================ */
/* --- 1. Step Controller --- */
.step-container {
  position: relative;
}
.step-stage {
  position: relative;
  overflow: hidden;
}
.step-stage [data-step] {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease;
  pointer-events: none;
}
.step-stage [data-step].active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}
.step-controls {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  margin-top: 1rem;
  padding: 0.5rem 1rem;
  background: var(--paper-2);
  border: 1px solid var(--hair-soft);
  border-radius: 4px;
  flex-wrap: wrap;
}
.step-btn {
  font-family: var(--mono);
  font-size: 0.9rem;
  padding: 0.3rem 0.75rem;
  min-height: 38px;
  background: var(--card);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 4px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
}
.step-btn:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
}
.step-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}
.step-dots {
  display: flex;
  gap: 0.4rem;
}
.step-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--hair);
  display: block;
  cursor: pointer;
  transition: background 0.15s ease;
}
.step-dot.active {
  background: var(--accent);
}
.step-label-text {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.05em;
  color: var(--ink-soft);
  text-transform: uppercase;
  margin-left: auto;
}

/* --- 2. Scrub Controller --- */
.scrub-container {
  margin-top: 1rem;
  padding: 1.25rem;
  background: var(--card);
  border: 1px solid var(--hair);
  border-radius: 4px;
}
.scrub-label-row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 0.75rem;
}
.scrub-label {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 600;
  color: var(--ink);
}
.scrub-value-readout {
  font-family: var(--mono);
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--paper-2);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
}
.scrub-slider-wrapper {
  position: relative;
  margin: 1.2rem 0 0.8rem;
}
.scrub-slider {
  -webkit-appearance: none;
  width: 100%;
  height: 6px;
  border-radius: 3px;
  background: var(--hair);
  outline: none;
  margin: 0;
}
.scrub-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 18px;
  height: 18px;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--paper);
  cursor: pointer;
  transition: transform 0.1s ease, background 0.15s ease;
  box-shadow: 0 1px 4px rgba(0,0,0,0.15);
}
.scrub-slider::-webkit-slider-thumb:hover {
  transform: scale(1.1);
  background: var(--accent);
}
.scrub-slider.at-target::-webkit-slider-thumb {
  background: var(--green) !important;
  box-shadow: 0 0 0 4px color-mix(in srgb, var(--green) 30%, transparent);
}
.scrub-marks {
  position: relative;
  height: 24px;
  margin-top: 0.4rem;
  border-top: 1px solid var(--hair-soft);
}
.scrub-mark {
  position: absolute;
  top: 4px;
  transform: translateX(-50%);
  font-family: var(--mono);
  font-size: 0.62rem;
  color: var(--ink-mute);
  text-transform: uppercase;
  white-space: nowrap;
}
.scrub-target-msg {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
  margin-top: 0.75rem;
  padding: 0.4rem 0.8rem;
  background: var(--paper-2);
  border-left: 3px solid var(--accent);
}
.scrub-target-msg.completed {
  border-left-color: var(--green);
  color: var(--green);
  font-weight: 600;
}

/* --- 3. Zoom Stage --- */
.zoom-stage {
  position: relative;
  width: 100%;
  overflow: hidden;
  border: 1px solid var(--hair);
  background: var(--paper);
  border-radius: 4px;
  aspect-ratio: 4 / 3;
}
.zoom-level-layer {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transition: opacity 0.35s ease, transform 0.35s ease, visibility 0.35s ease;
  display: flex;
  align-items: center;
  justify-content: center;
}
.zoom-level-layer.active {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
}
.zoom-level-layer svg {
  width: 100%;
  height: 100%;
}
.zoom-ring {
  fill: none;
  stroke: var(--accent);
  stroke-width: 1.5;
  stroke-dasharray: 4 4;
  animation: zoom-ring-pulse 2s infinite ease-in-out;
}
.zoom-rail {
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  z-index: 20;
  display: flex;
  flex-direction: column;
  background: color-mix(in srgb, var(--card) 85%, transparent);
  border: 1px solid var(--hair);
  border-radius: 20px;
  padding: 0.4rem;
  gap: 0.5rem;
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  backdrop-filter: blur(4px);
}
.zoom-rail-btn {
  width: 32px;
  height: 32px;
  border-radius: 50%;
  border: 1px solid var(--hair);
  background: var(--paper);
  color: var(--ink-soft);
  font-family: var(--mono);
  font-size: 0.65rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all 0.2s ease;
}
.zoom-rail-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}
.zoom-rail-btn.active {
  background: var(--accent);
  color: var(--paper);
  border-color: var(--accent);
}

@keyframes zoom-ring-pulse {
  0% { transform: scale(1); opacity: 0.8; }
  50% { transform: scale(1.05); opacity: 1; }
  100% { transform: scale(1); opacity: 0.8; }
}

@media (prefers-reduced-motion: reduce) {
  .step-stage [data-step],
  .zoom-level-layer {
    transition: none !important;
  }
  .zoom-ring {
    animation: none !important;
  }
}

/* ============================================================
   PRINT / PDF EXPORT — see INTERACTION_SPEC.md §3.5
   ============================================================ */
.print-only{display:none;}
@page{size:letter;margin:18mm 16mm;}

@media print{
  /* 1 — hide screen chrome & dead-on-paper controls */
  .topbar,.next-cue,.lightbox-overlay,.gc-tooltip,.textbook-nav,
  .w-buttons,.w-step-check-btn,.step-controls,
  .scrub-slider-wrapper,.scrub-marks,.scrub-target-msg,.zoom-rail,
  [data-recall-check],[data-recall-reveal],[data-recall-reset],
  [data-more],[data-peek],[data-scheme],
  .print-btn,.faded-model-collapsible>summary{display:none!important;}

  body{padding-top:0!important;background-image:none!important;background:#fff!important;color:#000!important;}

  /* 2 — force-reveal everything that is merely collapsed */
  .reveal{opacity:1!important;transform:none!important;}
  .more-body,.peek-box,.scheme,.reveal-box{
    max-height:none!important;opacity:1!important;overflow:visible!important;margin-top:1rem;
  }
  [data-predict] .opt[data-correct="true"]{border:2px solid var(--good)!important;}
  [data-predict] .opt[data-correct="true"]::after{content:" \2713";color:var(--good);font-weight:700;}

  /* 3 — motion primitives go static (print all frames in flow) */
  .step-stage{position:static!important;height:auto!important;overflow:visible!important;}
  .step-stage [data-step]{position:static!important;opacity:1!important;visibility:visible!important;transform:none!important;}
  .zoom-stage{height:auto!important;aspect-ratio:auto!important;overflow:visible!important;}
  .zoom-stage .zoom-level-layer{position:static!important;opacity:1!important;visibility:visible!important;margin-bottom:1rem;}
  .zoom-stage svg{transform:none!important;}
  .print-step-caption,.print-zoom-caption{display:block;font-family:var(--mono);font-size:.68rem;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);margin-bottom:.4rem;}

  /* 4 — page-break discipline (continuous flow, clean breaks) */
  .diagram,.exam-frame,[data-widget],.callout,.recall{break-inside:avoid;}
  h2,h3,h4{break-after:avoid;}

  /* 5 — print-only blocks injected by the core.js hook.
     faded-example nests everything inside .faded-layout (no flat direct
     children), so it's handled separately: keep the (JS-opened) model
     panel visible, hide only the raw "yours" input panel. */
  .print-only{display:block!important;}
  body.gc-printing [data-widget]:not([data-widget="faded-example"])>*:not(.print-only){display:none!important;}
  body.gc-printing [data-widget="faded-example"] .faded-yours{display:none!important;}

  /* 6 — static widget print-block styling (reuses existing card/opt idioms) */
  .w-print-static{margin-top:1rem;}
  .w-print-static .w-print-item{border-left:3px solid var(--good);background:var(--card);padding:.9rem 1.2rem;margin-bottom:.9rem;break-inside:avoid;}
  .w-print-static .w-print-item.wrong-context{border-left-color:var(--accent);}
  .w-print-static .w-opt{display:block;width:auto;margin-bottom:.5rem;}
  .w-print-static .w-print-feedback{font-family:var(--serif);font-size:.85rem;font-style:italic;color:var(--ink-mute);margin-top:.3rem;}
  .w-print-static .w-print-label{font-family:var(--mono);font-size:.68rem;letter-spacing:.08em;text-transform:uppercase;color:var(--accent);display:block;margin-bottom:.5rem;}

  /* 7 — print header + glossary appendix */
  .print-header{font-family:var(--mono);font-size:.78rem;letter-spacing:.06em;text-transform:uppercase;color:var(--ink-mute);border-bottom:1px solid var(--hair);padding-bottom:.6rem;margin-bottom:1.2rem;}
  .print-glossary{margin-top:2.5rem;padding-top:1.2rem;border-top:1px solid var(--hair);}
  .print-glossary dl{margin-top:.8rem;}
  .print-glossary dt{font-weight:700;color:var(--ink);margin-top:.7rem;}
  .print-glossary dd{margin-left:0;color:var(--ink-mute);}
  .print-glossary dd em{display:block;font-style:italic;font-size:.88em;margin-top:.15rem;}
}

/* ============================================================
   PERIODIC TABLE DROPDOWN DRAWER — see TODO.md §5
   ============================================================ */
.ptable-drawer-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(22, 32, 28, 0.4);
  z-index: 100;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
}
:root.dark .ptable-drawer-overlay {
  background: rgba(0, 0, 0, 0.6);
}
.ptable-drawer-overlay.open {
  opacity: 1;
  pointer-events: auto;
}

.ptable-drawer {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  width: 460px;
  max-width: 100vw;
  background-color: var(--paper);
  border-left: 1px solid var(--hair);
  z-index: 101;
  display: flex;
  flex-direction: column;
  box-shadow: -5px 0 25px rgba(0, 0, 0, 0.15);
  transform: translateX(100%);
  transition: transform 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
}
.ptable-drawer.open {
  transform: translateX(0);
}

.ptable-drawer-header {
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--hair);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--paper-2);
}
.ptable-drawer-header h3 {
  font-size: 1.2rem;
  margin: 0;
  font-family: var(--display);
}
.ptable-close-btn {
  background: none;
  border: none;
  font-size: 1.8rem;
  color: var(--ink-mute);
  cursor: pointer;
  line-height: 1;
  padding: 0;
  transition: color 0.2s;
}
.ptable-close-btn:hover {
  color: var(--accent);
}

.ptable-drawer-body {
  flex: 1;
  display: flex;
  flex-direction: column;
  overflow-y: auto;
  min-height: 0;
}

/* Control tabs for heatmaps */
.ptable-controls {
  padding: 1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  border-bottom: 1px solid var(--hair-soft);
}
.ptable-tabs {
  display: flex;
  background: var(--paper-2);
  border-radius: 4px;
  padding: 2px;
  gap: 2px;
}
.ptable-tab {
  flex: 1;
  border: none;
  background: none;
  font-family: var(--mono);
  font-size: 0.64rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-mute);
  padding: 0.4rem 0.2rem;
  cursor: pointer;
  border-radius: 3px;
  transition: all 0.2s;
  text-align: center;
}
.ptable-tab:hover {
  color: var(--ink);
}
.ptable-tab.active {
  background: var(--card);
  color: var(--accent);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
}

/* Scrollable container for standard 18-col layout */
.ptable-grid-container {
  overflow-x: auto;
  padding: 1.25rem;
  border-bottom: 1px solid var(--hair-soft);
}
.ptable-grid {
  display: grid;
  grid-template-columns: repeat(18, 1fr);
  grid-template-rows: repeat(4, 1fr);
  gap: 4px;
  min-width: 680px; /* Force standard proportions on narrow drawer */
}

/* Cells styling */
.ptable-cell {
  position: relative;
  aspect-ratio: 1;
  border: 1px solid var(--hair);
  border-radius: 4px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  user-select: none;
  transition: border-color 0.2s, transform 0.1s, box-shadow 0.2s, background-color 0.2s, color 0.2s;
  box-sizing: border-box;
}
.ptable-cell:hover {
  border-color: var(--accent);
  z-index: 5;
  transform: scale(1.08);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.1);
}
.ptable-cell.selected {
  border-color: var(--accent) !important;
  border-width: 2px !important;
  z-index: 6;
  transform: scale(1.08);
  box-shadow: 0 0 0 2px var(--accent-soft);
}
.ptable-cell .cell-z {
  font-family: var(--mono);
  font-size: 0.44rem;
  color: var(--ink-mute);
  position: absolute;
  top: 1px;
  left: 2px;
  pointer-events: none;
}
.ptable-cell .cell-sym {
  font-family: var(--mono);
  font-size: 0.72rem;
  font-weight: 700;
  line-height: 1.1;
  margin-top: 2px;
  pointer-events: none;
}
.ptable-cell .cell-val {
  font-family: var(--mono);
  font-size: 0.42rem;
  line-height: 1;
  margin-top: 1px;
  text-align: center;
  pointer-events: none;
}

/* Category styling (Default Kind view) */
.ptable-cell.kind-metal {
  background-color: var(--paper-3);
  color: var(--ink);
}
.ptable-cell.kind-metalloid {
  background-color: var(--paper-2);
  border-color: var(--ink-soft);
  color: var(--ink);
}
.ptable-cell.kind-nonmetal {
  background-color: var(--card);
  border-color: var(--ink-mute);
  color: var(--accent);
}
.ptable-cell.kind-noble {
  background-color: var(--card);
  opacity: 0.75;
  color: var(--ink-mute);
}

/* No data/null trend formatting */
.ptable-cell.no-data {
  background-image: repeating-linear-gradient(45deg, var(--hair-soft) 0, var(--hair-soft) 1px, transparent 0, transparent 4px);
  background-color: var(--card) !important;
  color: var(--ink-mute) !important;
  opacity: 0.55;
}

/* Legend inside body */
.ptable-legend {
  padding: 0 1.25rem 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  font-family: var(--mono);
  font-size: 0.6rem;
  color: var(--ink-mute);
}
.ptable-legend-gradient {
  flex: 1;
  max-width: 180px;
  height: 8px;
  border-radius: 4px;
  border: 1px solid var(--hair-soft);
}
.ptable-legend-swatches {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 0.75rem;
  justify-content: center;
}
.ptable-legend-swatch {
  display: flex;
  align-items: center;
  gap: 0.25rem;
}
.ptable-legend-chip {
  width: 10px;
  height: 10px;
  border-radius: 2px;
  border: 1px solid var(--hair-soft);
}

/* Detail Panel Styling */
.ptable-detail-panel {
  padding: 1.25rem;
  background-color: var(--paper-2);
  border-top: 1px solid var(--hair);
  min-height: 180px;
  display: flex;
  flex-direction: column;
}
.ptable-detail-placeholder {
  color: var(--ink-mute);
  font-size: 0.78rem;
  text-align: center;
  margin: auto;
  line-height: 1.5;
}
.ptable-detail-content {
  display: flex;
  gap: 1.25rem;
  width: 100%;
}
.ptable-detail-main {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.ptable-detail-atom-header {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
}
.ptable-detail-sym {
  font-family: var(--mono);
  font-size: 2.2rem;
  font-weight: 700;
  line-height: 1;
  color: var(--accent);
}
.ptable-detail-z {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink-mute);
}
.ptable-detail-name {
  font-family: var(--display);
  font-size: 1rem;
  font-weight: 700;
  color: var(--ink);
  line-height: 1.2;
}
.ptable-detail-kind-tag {
  align-self: flex-start;
  font-family: var(--mono);
  font-size: 0.54rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 1px 6px;
  border-radius: 3px;
  background: var(--card);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  margin-top: 0.15rem;
}
.ptable-detail-stats {
  margin-top: 0.5rem;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-family: var(--mono);
  font-size: 0.64rem;
}
.ptable-detail-stat-row {
  display: flex;
  justify-content: space-between;
  border-bottom: 1px dashed var(--hair-soft);
  padding-bottom: 2px;
}
.ptable-detail-stat-label {
  color: var(--ink-mute);
}
.ptable-detail-stat-val {
  font-weight: 600;
  color: var(--ink);
}
.ptable-detail-visual {
  width: 140px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.ptable-bohr-svg {
  width: 120px;
  height: 120px;
  display: block;
}
.ptable-bohr-cap {
  font-family: var(--mono);
  font-size: 0.54rem;
  color: var(--ink-mute);
  margin-top: 0.25rem;
  text-align: center;
}

@media (max-width: 480px) {
  .ptable-drawer {
    width: 100vw;
  }
}

.ptable-control-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.25rem;
}
.ptable-toggle-label {
  font-family: var(--mono);
  font-size: 0.6rem;
  color: var(--ink-soft);
  display: flex;
  align-items: center;
  gap: 0.35rem;
  cursor: pointer;
  user-select: none;
}
.ptable-toggle-label input {
  cursor: pointer;
  accent-color: var(--accent);
}

/* Reference Tray Tabs */
.ptable-drawer-tabs {
  display: flex;
  background: var(--paper-3);
  padding: 4px;
  gap: 4px;
  border-bottom: 1px solid var(--hair);
}
.ptable-drawer-tab {
  flex: 1;
  border: none;
  background: none;
  font-family: var(--display);
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--ink-mute);
  padding: 0.5rem 0.2rem;
  cursor: pointer;
  border-radius: 3px;
  transition: all 0.2s;
  text-align: center;
}
.ptable-drawer-tab:hover {
  color: var(--ink);
  background: var(--paper-2);
}
.ptable-drawer-tab.active {
  background: var(--card);
  color: var(--accent);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
}

.ptable-panel {
  display: none;
  flex: 1;
  flex-direction: column;
  min-height: 0;
}
.ptable-panel.active {
  display: flex;
}

/* Formulas & Tables Panel styling */
.ptable-formulas-container {
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
}
.ptable-ref-section {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}
.ptable-ref-section h4 {
  font-family: var(--display);
  font-size: 0.85rem;
  color: var(--accent);
  border-bottom: 1px solid var(--hair-soft);
  padding-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  font-weight: 700;
}
.ptable-ref-section p {
  font-size: 0.72rem;
  line-height: 1.5;
  color: var(--ink-soft);
}
.ptable-bridge-diagram {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--paper-2);
  padding: 0.75rem 0.5rem;
  border-radius: 4px;
  font-family: var(--mono);
  font-size: 0.58rem;
  margin-top: 0.25rem;
  text-align: center;
  border: 1px solid var(--hair-soft);
}
.ptable-bridge-node {
  background: var(--card);
  padding: 4px 8px;
  border-radius: 3px;
  border: 1px solid var(--hair);
  font-weight: 600;
  color: var(--ink);
}
.ptable-bridge-arrow {
  color: var(--ink-mute);
  display: flex;
  flex-direction: column;
  font-size: 0.46rem;
  line-height: 1.2;
}

/* Reference table styling */
.ptable-ref-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 0.64rem;
  margin-top: 0.25rem;
}
.ptable-ref-table th, .ptable-ref-table td {
  padding: 6px 8px;
  text-align: left;
  border-bottom: 1px solid var(--hair-soft);
}
.ptable-ref-table th {
  background: var(--paper-2);
  color: var(--ink-soft);
  font-weight: 600;
}
.ptable-ref-table tr:hover td {
  background: var(--paper-2);
}

/* Calculator Panel styling */
.ptable-calc-container {
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 1rem;
}
.ptable-calc-display-wrap {
  background: var(--card);
  border: 1px solid var(--hair);
  border-radius: 6px;
  padding: 0.75rem;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  min-height: 70px;
  justify-content: center;
}
.ptable-calc-expr {
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--ink-mute);
  min-height: 1rem;
  word-break: break-all;
  text-align: right;
  width: 100%;
}
.ptable-calc-result {
  font-family: var(--mono);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--ink);
  margin-top: 4px;
  word-break: break-all;
  text-align: right;
  width: 100%;
}
.ptable-calc-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 6px;
}
.ptable-calc-btn {
  border: 1px solid var(--hair);
  background: var(--card);
  font-family: var(--mono);
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--ink);
  height: 42px;
  border-radius: 4px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s;
}
.ptable-calc-btn:hover {
  background: var(--paper-2);
  border-color: var(--ink-soft);
}
.ptable-calc-btn:active {
  transform: scale(0.95);
}
.ptable-calc-btn.op {
  background: var(--paper-2);
  color: var(--accent);
}
.ptable-calc-btn.action {
  background: var(--paper-3);
  color: var(--ink);
}
.ptable-calc-btn.equals {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.ptable-calc-btn.equals:hover {
  background: var(--accent-soft);
}

/* Calculator Helper Tool styling */
.ptable-calc-helper {
  background: var(--paper-2);
  border: 1px solid var(--hair-soft);
  border-radius: 6px;
  padding: 0.75rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-top: 0.5rem;
}
.ptable-calc-helper-title {
  font-family: var(--display);
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--ink-soft);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 2px;
}
.ptable-calc-helper-row {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.ptable-calc-helper-field {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 2px;
}
.ptable-calc-helper-field span {
  font-family: var(--mono);
  font-size: 0.54rem;
  color: var(--ink-mute);
}
.ptable-calc-helper-field input {
  border: 1px solid var(--hair);
  background: var(--card);
  font-family: var(--mono);
  font-size: 0.72rem;
  padding: 4px 6px;
  border-radius: 3px;
  color: var(--ink);
  width: 100%;
}
.ptable-calc-helper-field input:focus {
  border-color: var(--accent);
  outline: none;
}
.ptable-calc-helper-arrow {
  font-family: var(--mono);
  font-size: 0.8rem;
  color: var(--ink-mute);
  margin-top: 10px;
}

/* --- Sort & Classify Widget --- */
.w-sort-container {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin: 1.5rem 0;
  width: 100%;
}
.w-sort-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1.5px solid var(--hair-soft);
  padding-bottom: 0.5rem;
}
.w-sort-status {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-soft);
}
.w-sort-card-stage {
  position: relative;
  background: var(--paper-2);
  border: 1px solid var(--hair);
  border-radius: 6px;
  min-height: 140px;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.5rem;
  box-shadow: inset 0 0 15px rgba(0,0,0,0.01);
  overflow: hidden;
}
.w-sort-card {
  font-family: var(--serif);
  font-size: 1.25rem;
  color: var(--ink);
  text-align: center;
  width: 100%;
  animation: w-card-enter 0.3s ease-out;
}
.w-sort-card strong.chem {
  font-family: var(--mono);
  font-size: 1.35rem;
}
.w-sort-bins {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
}
@media (min-width: 640px) {
  .w-sort-bins {
    grid-template-columns: repeat(3, 1fr);
  }
}
@media (min-width: 820px) {
  .w-sort-bins {
    grid-template-columns: repeat(5, 1fr);
  }
}
.w-sort-bin {
  font-family: var(--display);
  font-weight: 700;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 0.75rem 0.5rem;
  background: var(--card);
  border: 1px solid var(--hair);
  color: var(--ink-soft);
  cursor: pointer;
  border-radius: 4px;
  text-align: center;
  transition: all 0.2s ease;
  user-select: none;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 48px;
}
.w-sort-bin:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--ink);
  transform: translateY(-1px);
  box-shadow: 0 2px 4px rgba(0,0,0,0.04);
}
.w-sort-bin:active:not(:disabled) {
  transform: translateY(0);
}
.w-sort-bin:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}
.w-sort-bin.correct {
  border-color: var(--green) !important;
  color: var(--green) !important;
  background: color-mix(in srgb, var(--green) 6%, var(--paper)) !important;
  box-shadow: 0 0 8px color-mix(in srgb, var(--green) 15%, transparent);
}
.w-sort-bin.wrong {
  border-color: var(--accent) !important;
  color: var(--accent) !important;
  background: color-mix(in srgb, var(--accent) 6%, var(--paper)) !important;
  animation: w-shake 0.4s ease-in-out;
}

@keyframes w-card-enter {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}
@keyframes w-shake {
  0%, 100% { transform: translateX(0); }
  20%, 60% { transform: translateX(-4px); }
  40%, 80% { transform: translateX(4px); }
}

/* --- Diagnose the Error (.w-spot) --- */
.w-spot {
  cursor: pointer;
  transition: outline 0.15s ease, filter 0.15s ease, background-color 0.15s ease;
  outline: 2px transparent solid;
  outline-offset: 2px;
  border-radius: var(--radius-sm, 4px);
}
.w-spot:hover:not(.correct):not(.wrong) {
  outline: 2px dashed var(--accent);
}
.w-spot.selected {
  outline: 2px solid var(--accent);
}
.w-spot.correct {
  outline: 2px solid var(--green) !important;
  box-shadow: 0 0 6px color-mix(in srgb, var(--green) 25%, transparent);
}
.w-spot.wrong {
  outline: 2px solid var(--accent) !important;
  animation: w-shake 0.4s ease-in-out;
}

/* --- Construct with Live Validation --- */
.w-construct-container {
  display: flex;
  flex-direction: column;
  gap: 1.5rem;
  margin: 1.5rem auto;
  max-width: 520px;
  align-items: center;
}
.w-construct-pool {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem;
  justify-content: center;
  width: 100%;
}
.w-construct-pool-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--card-bg, rgba(0,0,0,0.02));
  border: 1px solid var(--dia-stroke, rgba(0,0,0,0.1));
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-md, 8px);
}
.w-construct-label {
  font-family: var(--font-chem, monospace);
  font-weight: 600;
  font-size: 1.1rem;
}
.w-construct-controls {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.w-construct-btn {
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: 1px solid var(--dia-stroke, rgba(0,0,0,0.2));
  background: var(--paper);
  color: var(--ink);
  font-size: 1rem;
  font-weight: bold;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease, border-color 0.15s ease;
}
.w-construct-btn:hover:not(:disabled) {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.w-construct-btn:disabled {
  opacity: 0.3;
  cursor: not-allowed;
}
.w-construct-val {
  font-family: var(--font-chem, monospace);
  font-size: 1.1rem;
  min-width: 1.5rem;
  text-align: center;
}
.w-construct-workspace {
  width: 100%;
  min-height: 80px;
  border: 2px dashed var(--dia-stroke, rgba(0,0,0,0.15));
  border-radius: var(--radius-lg, 12px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 1rem;
  background: var(--paper);
  gap: 0.75rem;
}
.w-construct-formula {
  font-family: var(--font-chem, monospace);
  font-size: 1.8rem;
  font-weight: bold;
  letter-spacing: 0.05em;
}
.w-construct-formula:empty::before {
  content: "Add components to build formula";
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: normal;
  color: var(--ink);
  opacity: 0.5;
}
.w-construct-badge {
  display: inline-flex;
  align-items: center;
  padding: 0.25rem 0.75rem;
  font-family: var(--font-sans);
  font-size: 0.85rem;
  font-weight: 600;
  border-radius: 99px;
  border: 1px solid transparent;
}
.w-construct-badge.unbalanced {
  border-color: var(--accent);
  color: var(--accent);
  background: color-mix(in srgb, var(--accent) 6%, var(--paper));
}
.w-construct-badge.balanced {
  border-color: var(--green);
  color: var(--green);
  background: color-mix(in srgb, var(--green) 6%, var(--paper));
}
.w-construct-badge:empty {
  display: none;
}

/* --- Quick Check (Review Mode) --- */
/* --- Quick Check & Cram View (Review Modes) --- */
.quick-check-toggle, .cram-view-toggle {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: none;
  border: 1px solid var(--dia-stroke, rgba(0,0,0,0.15));
  border-radius: var(--radius-sm, 6px);
  padding: 0.35rem 0.6rem;
  color: var(--ink);
  cursor: pointer;
  font-family: var(--font-ui, sans-serif);
  font-size: 0.85rem;
  font-weight: 500;
  transition: all 0.15s ease;
  margin-right: 0.5rem;
}
.quick-check-toggle:hover, .cram-view-toggle:hover {
  background: var(--card-bg, rgba(0,0,0,0.04));
  border-color: var(--ink);
}
.quick-check-toggle.active {
  background: var(--green);
  color: #fff;
  border-color: var(--green);
}
.cram-view-toggle.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.quick-check-toggle svg, .cram-view-toggle svg {
  width: 15px;
  height: 15px;
}
@media (max-width: 580px) {
  .quick-check-toggle span, .cram-view-toggle span {
    display: none;
  }
  .quick-check-toggle, .cram-view-toggle {
    padding: 0.35rem;
    margin-right: 0.25rem;
  }
}

/* Exclude narrative prose when Quick Check is active */
body.quick-check-active p:not(.w-prompt):not(.w-feedback):not(.w-opt):not(.w-progress-hint):not(.d-cap):not(.diagram-cap):not(.lede):not(.w-construct-label):not(.w-construct-val),
body.quick-check-active ul:not(.w-sort-bins):not(.w-construct-pool):not(.toc-drop ul):not(.synopsis-claims ul):not(.synopsis-checklist ul),
body.quick-check-active ol,
body.quick-check-active blockquote,
body.quick-check-active .meta-strip,
body.quick-check-active h2:not(.w-prompt h2):not(.w-prompt > h2):not(.widget-section h2):not(.w-sort-card h2) {
  display: none !important;
}

/* --- One-Screen Synopsis --- */
.synopsis-wrapper {
  margin: 1.5rem 0;
  width: 100%;
}
.w-btn-synopsis {
  width: 100%;
  text-align: left;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-family: var(--font-ui, sans-serif);
  font-weight: 600;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md, 8px) !important;
  background: var(--paper-2, rgba(0,0,0,0.01));
}
.synopsis-body {
  border: 1px solid var(--dia-stroke, rgba(0,0,0,0.15));
  border-radius: var(--radius-lg, 12px);
  padding: 1.5rem;
  background: var(--paper);
  margin-top: 0.5rem;
  box-shadow: var(--shadow-sm);
}
.synopsis-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}
.synopsis-claims h4,
.synopsis-figure h4,
.synopsis-checklist h4 {
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-family: var(--font-ui, sans-serif);
  font-weight: 700;
  color: var(--ink);
  border-bottom: 1px solid var(--dia-stroke, rgba(0,0,0,0.1));
  padding-bottom: 0.35rem;
}
.synopsis-claims ul {
  padding-left: 1.25rem;
  margin: 0;
}
.synopsis-claims li {
  margin-bottom: 0.5rem;
  line-height: 1.4;
  font-size: 0.95rem;
}
.synopsis-figure {
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.synopsis-figure svg,
.synopsis-figure img {
  max-width: 100%;
  height: auto;
  max-height: 120px;
}
.synopsis-checklist ul {
  list-style: none;
  padding-left: 0;
  margin: 0;
}
.synopsis-checklist li {
  display: flex;
  align-items: flex-start;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
  line-height: 1.4;
}
.synopsis-checklist input[type="checkbox"] {
  margin-top: 0.2rem;
  accent-color: var(--green);
}

/* --- Practice Review Grading Buttons --- */
.btn-forgot {
  background: var(--bad, #e06c75);
  color: #fff !important;
  border-color: var(--bad, #e06c75) !important;
}
.btn-forgot:hover {
  background: color-mix(in srgb, var(--bad, #e06c75) 80%, black) !important;
  border-color: color-mix(in srgb, var(--bad, #e06c75) 80%, black) !important;
}
.btn-hard {
  background: var(--warn, #d19a66);
  color: #fff !important;
  border-color: var(--warn, #d19a66) !important;
}
.btn-hard:hover {
  background: color-mix(in srgb, var(--warn, #d19a66) 80%, black) !important;
  border-color: color-mix(in srgb, var(--warn, #d19a66) 80%, black) !important;
}
.btn-easy {
  background: var(--good, #98c379);
  color: #fff !important;
  border-color: var(--good, #98c379) !important;
}
.btn-easy:hover {
  background: color-mix(in srgb, var(--good, #98c379) 80%, black) !important;
  border-color: color-mix(in srgb, var(--good, #98c379) 80%, black) !important;
}