/* ============================================================
   Shared interactive styling — quiz engine, plus the
   subject-specific widgets. Loaded in addition to style.css.
   ============================================================ */

/* ---- syllabus tier badges ---------------------------------- */
.tier{
  display:inline-block;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;padding:3px 8px;
  border:1.5px solid var(--rule);color:var(--ink-soft);vertical-align:middle;
  margin-left:8px;white-space:nowrap;
}
.tier.g2{border-color:#B07A2A;color:#8A5E18;background:rgba(240,135,30,.1)}
.tier.ext{border-color:var(--cool);color:var(--cool);background:rgba(46,122,140,.08)}

.tierblock{border-left:6px solid var(--rule);padding-left:16px;margin:0 0 18px}
.tierblock.g2{border-left-color:#B07A2A}
.tierblock.ext{border-left-color:var(--cool)}
.tierblock > h3{
  font-family:"Bricolage Grotesque",sans-serif;font-size:18px;margin:0 0 4px;font-weight:700;
}
.tierblock > .tier-note{font-size:12px;color:var(--ink-soft);margin:0 0 12px}

/* optional-content toggle */
.optbar{
  display:flex;gap:10px;flex-wrap:wrap;align-items:center;
  padding:14px 24px;border-bottom:1.5px solid var(--ink);
  background:rgba(240,244,248,.7);font-size:13px;
}
.optbar .optlabel{font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft)}
body.hide-g2 [data-tier="g2"]{display:none}
body.hide-ext [data-tier="ext"]{display:none}

/* ---- generic widget shell ---------------------------------- */
.sim{
  border:1.5px solid var(--ink);background:rgba(240,244,248,.86);
  margin:0 0 22px;box-shadow:4px 4px 0 rgba(15,36,54,.1);
}
.sim-head{
  padding:12px 16px;border-bottom:1.5px solid var(--ink);
  display:flex;justify-content:space-between;align-items:center;gap:12px;flex-wrap:wrap;
}
.sim-head h4{
  margin:0;font-family:"Space Mono",monospace;font-size:11px;
  letter-spacing:.12em;text-transform:uppercase;color:var(--ink-soft);font-weight:400;
}
.sim-body{padding:16px}
.sim-foot{padding:12px 16px;border-top:1.5px dotted var(--rule);font-size:13px;color:var(--ink-soft)}
.sim-row{display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.sim-row + .sim-row{margin-top:10px}
.sim svg{display:block;max-width:100%;height:auto}

.picker{display:flex;gap:8px;flex-wrap:wrap}
.picker button{font-size:11px;padding:9px 12px;min-height:40px}

.readout-grid{
  display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:12px;margin-top:14px;
}
.readout-box{border:1.5px solid var(--ink);background:#F7FAFC;padding:10px 12px}
.readout-box .rl{
  display:block;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);margin-bottom:4px;
}
.readout-box .rv{font-family:"Space Mono",monospace;font-weight:700;font-size:15px}

/* word equation display */
.wordeq{
  font-family:"Space Mono",monospace;font-weight:700;font-size:14px;line-height:1.9;
  background:#F7FAFC;border:1.5px solid var(--ink);padding:12px 14px;margin:14px 0 0;
  overflow-x:auto;
}
.wordeq .rx{color:var(--ink)}
.wordeq .px{color:var(--hot)}
.wordeq .arrow{color:var(--charge);padding:0 6px}
.wordeq .cond{font-size:11px;color:var(--ink-soft)}

/* ---- atom lab ---------------------------------------------- */
.atomgrid{display:grid;grid-template-columns:1fr auto 1fr;gap:12px;align-items:center}
@media (max-width:560px){.atomgrid{grid-template-columns:1fr;gap:8px}}
.atomgrid .side{border:1.5px solid var(--ink);background:#F7FAFC;padding:12px;min-height:130px}
.atomgrid .side h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);font-weight:400;text-align:center;
}
.atomgrid .mid{
  font-family:"Space Mono",monospace;font-size:26px;color:var(--charge);text-align:center;font-weight:700;
}
@media (max-width:560px){.atomgrid .mid{font-size:20px;transform:rotate(90deg)}}

.counttable{width:100%;border-collapse:collapse;font-size:13px;margin-top:14px}
.counttable th{
  font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.08em;
  text-transform:uppercase;color:var(--ink-soft);font-weight:400;text-align:left;
  padding:6px 8px;border-bottom:1.5px solid var(--ink);
}
.counttable td{padding:7px 8px;border-bottom:1px dotted var(--rule)}
.counttable input{
  width:58px;font-family:"Space Mono",monospace;font-size:14px;font-weight:700;
  padding:6px 8px;border:1.5px solid var(--rule);background:#F7FAFC;color:var(--ink);
}
.counttable input:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px;border-color:var(--ink)}
.counttable input.ok{border-color:var(--cool);background:rgba(46,122,140,.1)}
.counttable input.no{border-color:var(--hot);background:rgba(217,63,43,.1)}
.counttable .mk{font-family:"Space Mono",monospace;font-weight:700}
.counttable .mk.ok{color:var(--cool)}
.counttable .mk.no{color:var(--hot)}

/* ---- pH lab ------------------------------------------------- */
.ph-scale{
  height:30px;border:1.5px solid var(--ink);position:relative;
  background:linear-gradient(90deg,
    #D62828 0%, #E85D2A 14%, #EDA13C 22%, #E8D93E 36%,
    #A9CC4A 45%, #4FA85C 50%, #3FA79B 60%, #3E7FBF 72%,
    #3E4A9C 86%, #5B3E9C 100%);
}
.ph-needle{
  position:absolute;top:-12px;width:0;height:0;transform:translateX(-50%);
  border-left:9px solid transparent;border-right:9px solid transparent;
  border-top:14px solid var(--ink);transition:left .45s cubic-bezier(.4,1.3,.5,1);
}
.ph-ticks{display:flex;justify-content:space-between;font-family:"Space Mono",monospace;font-size:10px;color:var(--ink-soft);margin-top:4px}

.swatch{
  display:inline-block;width:22px;height:22px;border:1.5px solid var(--ink);
  vertical-align:middle;margin-right:8px;transition:background .45s ease;flex-shrink:0;
}
.litmus-row{display:flex;align-items:center;gap:8px;font-size:13px;margin-top:8px}
.litmus-strip{
  width:34px;height:16px;border:1.5px solid var(--ink);transition:background .5s ease;flex-shrink:0;
}

/* ---- acid bench --------------------------------------------- */
.bench{display:grid;grid-template-columns:1fr 1fr;gap:16px}
@media (max-width:600px){.bench{grid-template-columns:1fr}}
.bench-col h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);font-weight:400;
}
.gastest{margin-top:14px;padding-top:14px;border-top:1.5px dotted var(--rule)}
.gastest .verdict{
  margin-top:10px;padding:10px 12px;border-left:4px solid var(--rule);
  background:#F7FAFC;font-size:13px;
}
.gastest .verdict.good{border-left-color:var(--cool)}
.gastest .verdict.bad{border-left-color:var(--hot)}

.fizz{opacity:0}
.fizz.on{animation:fizzUp 1.5s ease-in infinite}
@keyframes fizzUp{
  0%{opacity:0;transform:translateY(4px)}
  20%{opacity:.95}
  100%{opacity:0;transform:translateY(-42px)}
}

/* ---- electro lab -------------------------------------------- */
.gasbubble{opacity:0}
.gasbubble.on{animation:gasUp 2s linear infinite}
@keyframes gasUp{
  0%{opacity:0;transform:translateY(0)}
  15%{opacity:.9}
  100%{opacity:0;transform:translateY(-56px)}
}
.plate-layer{transition:height .6s ease, y .6s ease}
.ion{opacity:.9}

/* ---- ocean lab ---------------------------------------------- */
.shell-wrap{display:flex;gap:20px;align-items:flex-end;justify-content:center;flex-wrap:wrap}
.shell-card{text-align:center}
.shell-card .cap{font-family:"Space Mono",monospace;font-size:11px;color:var(--ink-soft);margin-top:6px}

/* ---- interactive question engine ---------------------------- */
.qz{border:1.5px solid var(--ink);background:#F7FAFC;margin:0 0 18px;box-shadow:3px 3px 0 rgba(15,36,54,.08)}
.qz-head{
  padding:12px 16px;border-bottom:1.5px dotted var(--rule);
  display:flex;gap:10px;align-items:baseline;flex-wrap:wrap;
}
.qz-num{font-family:"Space Mono",monospace;font-weight:700;color:var(--charge);flex-shrink:0}
.qz-marks{
  margin-left:auto;font-family:"Space Mono",monospace;font-size:11px;
  color:var(--ink-soft);border:1px solid var(--rule);padding:2px 7px;flex-shrink:0;
}
.qz-stem{padding:14px 16px 0;font-size:15px;line-height:1.5}
.qz-stem p{margin:0 0 10px}
.qz-body{padding:12px 16px 16px}

.opts{display:flex;flex-direction:column;gap:8px;margin-top:6px}
.opt{
  display:flex;gap:10px;align-items:flex-start;text-align:left;width:100%;
  border:1.5px solid var(--rule);background:#FFF;padding:11px 13px;cursor:pointer;
  font-family:"Spline Sans",system-ui,sans-serif;font-size:14px;color:var(--ink);
  min-height:44px;line-height:1.45;
}
.opt:hover:not(:disabled){border-color:var(--ink);background:rgba(240,135,30,.06)}
.opt:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px}
.opt .key{
  font-family:"Space Mono",monospace;font-weight:700;color:var(--ink-soft);flex-shrink:0;
}
.opt[aria-pressed="true"]{border-color:var(--ink);background:rgba(240,135,30,.14)}
.opt.correct{border-color:var(--cool);background:rgba(46,122,140,.14)}
.opt.correct .key{color:var(--cool)}
.opt.wrong{border-color:var(--hot);background:rgba(217,63,43,.1)}
.opt.wrong .key{color:var(--hot)}
/* Once answered the options are disabled, but they must stay fully legible —
   the option the student picked is the one they most need to re-read.
   -webkit-text-fill-color is required to beat WebKit's disabled greying. */
.opt:disabled{
  cursor:default;opacity:1;color:var(--ink);-webkit-text-fill-color:var(--ink);
}
.opt:disabled .key{-webkit-text-fill-color:currentColor}
.eqtile:disabled, .eqslot:disabled{
  opacity:1;color:var(--ink);-webkit-text-fill-color:var(--ink);cursor:default;
}
.eqtile.used{opacity:.35}

/* word-equation builder */
.eqbuild{margin-top:10px}
.eqslots{
  display:flex;gap:8px;flex-wrap:wrap;align-items:center;
  border:1.5px dashed var(--rule);background:#FFF;padding:12px;min-height:58px;
}
.eqslot{
  min-width:104px;min-height:38px;border:1.5px solid var(--rule);background:var(--paper-2);
  display:inline-flex;align-items:center;justify-content:center;padding:7px 10px;
  font-family:"Space Mono",monospace;font-size:12px;cursor:pointer;color:var(--ink);
}
.eqslot.filled{background:#FFF;border-color:var(--ink);border-style:solid}
.eqslot.correct{border-color:var(--cool);background:rgba(46,122,140,.14)}
.eqslot.wrong{border-color:var(--hot);background:rgba(217,63,43,.1)}
.eqslot:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px}
.eqop{font-family:"Space Mono",monospace;font-weight:700;color:var(--charge);font-size:15px}
.eqbank{display:flex;gap:8px;flex-wrap:wrap;margin-top:10px}
.eqtile{
  border:1.5px solid var(--ink);background:#FFF;padding:9px 12px;cursor:pointer;
  font-family:"Space Mono",monospace;font-size:12px;color:var(--ink);min-height:40px;
}
.eqtile:hover:not(:disabled){background:var(--ink);color:var(--paper)}
.eqtile:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px}
.eqtile.used{opacity:.3;cursor:default;pointer-events:none}

/* sorting bins */
.bins{display:grid;grid-template-columns:1fr 1fr;gap:12px;margin-top:10px}
@media (max-width:520px){.bins{grid-template-columns:1fr}}
.bin{border:1.5px solid var(--ink);background:#FFF;padding:12px;min-height:90px}
.bin h6{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);font-weight:400;
}
.bin .chip{
  display:inline-block;border:1.5px solid var(--rule);background:var(--paper-2);
  padding:5px 9px;margin:0 6px 6px 0;font-size:12px;
}
.bin .chip.correct{border-color:var(--cool);background:rgba(46,122,140,.14)}
.bin .chip.wrong{border-color:var(--hot);background:rgba(217,63,43,.1)}

/* feedback + actions */
.qz-fb{margin-top:14px;padding:12px 14px;border-left:4px solid var(--ink-soft);background:var(--paper);font-size:14px}
.qz-fb.good{border-left-color:var(--cool)}
.qz-fb.bad{border-left-color:var(--hot)}
.qz-fb p{margin:0 0 8px}
.qz-fb p:last-child{margin:0}
.qz-fb .mark{font-family:"Space Mono",monospace;font-weight:700;font-size:12px;text-transform:uppercase;letter-spacing:.08em}
.qz-fb.good .mark{color:var(--cool)}
.qz-fb.bad .mark{color:var(--hot)}
.qz-acts{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px;align-items:center}
.qz-acts .spacer{flex:1}

/* ============================================================
   Literature
   ============================================================ */

/* quoted extract — deliberately short, for criticism and review */
.extract{
  border-left:6px solid var(--charge);background:#F7FAFC;
  padding:16px 20px;margin:0 0 18px;
}
.extract p{margin:0;font-size:16px;line-height:1.85;white-space:pre-line}
.extract .cite{
  display:block;margin-top:12px;font-family:"Space Mono",monospace;
  font-size:11px;letter-spacing:.06em;color:var(--ink-soft);white-space:normal;
}

.booknote{
  display:flex;gap:10px;align-items:flex-start;
  border:1.5px dashed var(--rule);background:rgba(240,135,30,.06);
  padding:12px 14px;margin:0 0 18px;font-size:13px;color:var(--ink-soft);
}
.booknote strong{color:var(--ink)}

/* the turn — before/after panel */
.turnbox{display:grid;grid-template-columns:1fr auto 1fr;gap:14px;align-items:center;margin:0 0 20px}
@media (max-width:620px){.turnbox{grid-template-columns:1fr;gap:8px}}
.turnbox .half{border:1.5px solid var(--ink);background:#F7FAFC;padding:14px 16px}
.turnbox .half h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);font-weight:400;
}
.turnbox .half p{margin:0;font-size:14px}
.turnbox .pivot{
  font-family:"Space Mono",monospace;font-size:22px;color:var(--charge);
  text-align:center;font-weight:700;
}
@media (max-width:620px){.turnbox .pivot{transform:rotate(90deg)}}

/* scope ladder: Self -> Others -> Nation */
.scoperow{
  display:grid;grid-template-columns:118px 1fr;gap:14px;
  border-top:1.5px solid var(--rule);padding:13px 0;align-items:baseline;
}
.scoperow:last-child{border-bottom:1.5px solid var(--rule)}
.scoperow .scope{
  font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--charge);
}
.scoperow .what strong{display:block;margin-bottom:3px}
.scoperow .what span{font-size:14px;color:var(--ink-soft)}
@media (max-width:520px){.scoperow{grid-template-columns:1fr;gap:4px}}

/* hotspot — clickable lines */
.hotlines{display:flex;flex-direction:column;gap:4px;margin-top:8px}
.hotline{
  display:flex;gap:12px;align-items:flex-start;text-align:left;width:100%;
  border:1.5px solid transparent;border-left-color:var(--rule);
  background:#FFF;padding:9px 12px;cursor:pointer;min-height:40px;
  font-family:"Spline Sans",system-ui,sans-serif;font-size:15px;color:var(--ink);
  line-height:1.5;
}
.hotline:hover:not(:disabled){border-color:var(--rule);border-left-color:var(--charge);background:rgba(240,135,30,.06)}
.hotline:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px}
.hotline[aria-pressed="true"]{border-color:var(--ink);background:rgba(240,135,30,.14)}
.hotline.correct{border-color:var(--cool);background:rgba(46,122,140,.14)}
.hotline.wrong{border-color:var(--hot);background:rgba(217,63,43,.1)}
.hotline:disabled{cursor:default;opacity:1;color:var(--ink);-webkit-text-fill-color:var(--ink)}
.hotline .hl-n{
  font-family:"Space Mono",monospace;font-size:11px;color:var(--ink-soft);
  flex:none;width:18px;padding-top:3px;
}

/* P.E.E. builder */
.peesteps{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:4px 0 16px}
.peechip{
  font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.08em;
  text-transform:uppercase;border:1.5px solid var(--rule);color:var(--ink-soft);
  padding:5px 11px;
}
.peechip.now{border-color:var(--ink);background:var(--ink);color:#F7FAFC}
.peechip.done{border-color:var(--cool);color:var(--cool);background:rgba(46,122,140,.1)}
.peearrow{font-family:"Space Mono",monospace;color:var(--charge);font-weight:700}
.peeprompt{margin:0 0 10px;font-size:15px}
.peepara{
  border:1.5px solid var(--ink);background:#FFF;padding:16px 18px;margin-top:16px;
  box-shadow:4px 4px 0 rgba(15,36,54,.1);
}
.peepara h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.12em;text-transform:uppercase;color:var(--charge);font-weight:400;
}
.peepara p{margin:0;font-size:15px;line-height:1.65}

/* ---- numeric answer ----------------------------------------- */
.numrow{display:flex;align-items:center;gap:10px;margin-top:8px;flex-wrap:wrap}
.numin{
  font-family:"Space Mono",monospace;font-size:17px;font-weight:700;
  padding:11px 14px;width:180px;max-width:100%;
  border:1.5px solid var(--rule);background:#FFF;color:var(--ink);
}
.numin::placeholder{font-weight:400;font-size:14px;color:var(--ink-soft)}
.numin:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px;border-color:var(--ink)}
.numin:disabled{opacity:1;color:var(--ink);-webkit-text-fill-color:var(--ink)}
.numin.ok{border-color:var(--cool);background:rgba(46,122,140,.12)}
.numin.no{border-color:var(--hot);background:rgba(217,63,43,.1)}
.numunit{
  font-family:"Space Mono",monospace;font-size:16px;font-weight:700;color:var(--ink-soft);
}

/* ---- circuit symbol sheet ------------------------------------ */
.symsheet .sym-box{fill:#FFF;stroke:var(--ink);stroke-width:1.5}
.symsheet .sym-w{fill:none;stroke:var(--ink);stroke-width:2.4;stroke-linecap:round}
.symsheet .sym-f{fill:#FFF;stroke:var(--ink);stroke-width:2.4}
.symsheet .sym-n{
  font-family:"Space Mono",monospace;font-size:15px;font-weight:700;
  fill:#F7FAFC;text-anchor:middle;
}
.symsheet .sym-c{fill:var(--charge);stroke:var(--ink);stroke-width:2}
.symsheet .sym-t{
  font-family:"Space Mono",monospace;font-size:13px;font-weight:700;
  fill:var(--ink);text-anchor:middle;
}

/* ---- diagram labelling -------------------------------------- */
.labelfig{
  border:1.5px solid var(--ink);background:#FFF;padding:14px;margin:4px 0 16px;
  display:flex;justify-content:center;
}
.labelfig svg{max-width:100%;height:auto}
.labelrows{display:grid;grid-template-columns:repeat(auto-fit,minmax(230px,1fr));gap:10px}
.labelrow{
  display:flex;align-items:center;gap:10px;
  border:1.5px solid var(--rule);background:#FFF;padding:9px 11px;
}
.labelrow.ok{border-color:var(--cool);background:rgba(46,122,140,.09)}
.labelrow.no{border-color:var(--hot);background:rgba(217,63,43,.08)}
.labelrow .lnum{
  font-family:"Space Mono",monospace;font-weight:700;font-size:14px;
  width:26px;height:26px;flex:none;border:1.5px solid var(--ink);border-radius:50%;
  display:flex;align-items:center;justify-content:center;background:var(--charge);color:#F7FAFC;
}
.labelrow .lsel{
  flex:1;min-width:0;font-family:inherit;font-size:14px;padding:8px 9px;
  border:1.5px solid var(--rule);background:#F7FAFC;color:var(--ink);min-height:40px;
}
.labelrow .lsel:focus-visible{outline:2.5px solid var(--hot);outline-offset:2px}
.labelrow .lsel:disabled{opacity:1;color:var(--ink);-webkit-text-fill-color:var(--ink)}
.labelrow .lmark{font-family:"Space Mono",monospace;font-weight:700;width:16px;flex:none}
.labelrow .lmark.ok{color:var(--cool)}
.labelrow .lmark.no{color:var(--hot)}

/* plug diagram colours */
.plug-body{fill:#F2F5F8;stroke:var(--ink);stroke-width:2.4}
.plug-pin{fill:#C9B47A;stroke:var(--ink);stroke-width:2}
.plug-term{fill:#D8C48E;stroke:var(--ink);stroke-width:2}
.w-earth{stroke:#C8D93A;stroke-width:7;fill:none;stroke-linecap:round}
.w-earth-b{stroke:#4E9E4E;stroke-width:7;fill:none;stroke-linecap:round;stroke-dasharray:11 11}
.w-live{stroke:#7B4A2A;stroke-width:7;fill:none;stroke-linecap:round}
.w-neutral{stroke:#2E6BB8;stroke-width:7;fill:none;stroke-linecap:round}
.plug-fuse{fill:#E8DCC0;stroke:var(--ink);stroke-width:2}
.plug-grip{fill:#3E4650;stroke:var(--ink);stroke-width:2}
.plug-cable{fill:#EDEFF2;stroke:var(--ink);stroke-width:2.4}
.callout-num circle{fill:var(--charge);stroke:var(--ink);stroke-width:2}
.callout-num text{
  font-family:"Space Mono",monospace;font-size:14px;font-weight:700;
  fill:#F7FAFC;text-anchor:middle;
}
.callout-line{stroke:var(--ink);stroke-width:1.5;stroke-dasharray:4 3;fill:none}

/* wrong-answer derivation: why it was wrong, then how to get there */
.derive{
  margin-top:12px;padding:12px 14px;
  border:1.5px solid var(--rule);background:#FFF;
}
.derive .why{margin:0 0 10px;font-size:14px}
.derive h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.12em;text-transform:uppercase;color:var(--charge);font-weight:400;
}
.derive ol{margin:0;padding-left:20px;font-size:14px}
.derive ol li{margin-bottom:7px;line-height:1.5}
.derive ol li:last-child{margin-bottom:0}
.derive .ansline{
  margin:11px 0 0;padding-top:10px;border-top:1.5px dotted var(--rule);
  font-size:14px;
}
.derive .ansline strong{color:var(--cool)}

.model{margin-top:12px;border:1.5px solid var(--ink);background:#FFF}
.model > summary{
  cursor:pointer;list-style:none;padding:10px 13px;
  font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.08em;
  text-transform:uppercase;color:var(--ink-soft);
}
.model > summary::-webkit-details-marker{display:none}
.model > summary::after{content:" ▸";color:var(--charge)}
.model[open] > summary::after{content:" ▾"}
.model > summary:focus-visible{outline:2.5px solid var(--hot);outline-offset:-2px}
.model .mbody{padding:0 13px 13px;font-size:14px}
.model .mbody p{margin:0 0 8px}
.model .mbody .pt{
  display:block;padding-left:16px;border-left:2px solid var(--charge);margin:0 0 8px;
}

/* score panel */
.scorebar{
  position:sticky;top:0;z-index:5;
  display:flex;gap:14px;align-items:center;flex-wrap:wrap;
  padding:12px 24px;border-bottom:1.5px solid var(--ink);
  background:var(--ink);color:#F7FAFC;
  font-family:"Space Mono",monospace;font-size:12px;
}
.scorebar .sc{font-weight:700;color:var(--charge)}
.scorebar .bar{
  flex:1;min-width:110px;height:8px;background:rgba(247,250,252,.2);overflow:hidden;
}
.scorebar .bar span{display:block;height:100%;background:var(--charge);width:0;transition:width .4s ease}
.scorebar button{border-color:#F7FAFC;color:#F7FAFC;min-height:36px;padding:7px 11px;font-size:11px}
.scorebar button:hover{background:#F7FAFC;color:var(--ink)}

/* ---- concept map -------------------------------------------- */
.cmap{padding:8px 24px 24px;overflow-x:auto}
.cmap svg{min-width:680px}
.cmap .nd rect{fill:#4A3C8C;stroke:none}
.cmap .nd text{fill:#F7FAFC;font-family:"Spline Sans",sans-serif;font-size:12px;text-anchor:middle}
.cmap .nd.root rect{fill:var(--hot)}
.cmap .nd.accent rect{fill:var(--charge)}
.cmap .lk{stroke:var(--ink-soft);stroke-width:1.5;fill:none}
.cmap .lbl{font-family:"Space Mono",monospace;font-size:9px;fill:var(--ink-soft)}

/* ============================================================
   Chemistry: Diversity of matter (Chapter 3)
   ============================================================ */

/* periodic table explorer */
.ptgrid{
  display:grid;grid-template-columns:repeat(18,minmax(0,1fr));grid-auto-rows:34px;gap:3px;
  margin-bottom:12px;
}
.pt-cell{
  display:flex;flex-direction:column;align-items:center;justify-content:center;gap:0;
  padding:0;min-height:0;height:34px;border:1.2px solid var(--ink);cursor:pointer;
  font-family:"Space Mono",monospace;line-height:1;box-shadow:none;
}
.pt-cell .pt-z{font-size:7px;color:var(--ink-soft);line-height:1}
.pt-cell .pt-sym{font-size:11px;font-weight:700;color:var(--ink);line-height:1.1}
.pt-metal{background:#F5E27A}
.pt-non{background:#9FD0E8}
.pt-cell:hover{filter:brightness(.94)}
.pt-cell[aria-pressed="true"]{outline:2.5px solid var(--hot);outline-offset:1px;z-index:1;box-shadow:none;transform:none}
.pt-cell.pt-metal[aria-pressed="true"]{background:#F5E27A}
.pt-cell.pt-non[aria-pressed="true"]{background:#9FD0E8}
.pt-cell[aria-pressed="true"] .pt-sym{color:var(--ink)}
.pt-cell[aria-pressed="true"] .pt-z{color:var(--ink-soft)}
.ptscroll{overflow-x:auto;margin-bottom:12px;-webkit-overflow-scrolling:touch}
.ptscroll .ptgrid{min-width:600px;margin-bottom:0}
@media (max-width:560px){
  .ptgrid{grid-auto-rows:30px}
  .pt-cell{height:30px}.pt-cell .pt-z{display:none}.pt-cell .pt-sym{font-size:10px}
  .pt-keyrow::after{content:"Swipe the table sideways";font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.08em;text-transform:uppercase}
}
.pt-keyrow{display:flex;justify-content:space-between;gap:12px;flex-wrap:wrap;margin-bottom:10px;font-size:12px;color:var(--ink-soft)}
.pt-key{display:flex;gap:16px;flex-wrap:wrap;align-items:center}
.pt-key i{display:inline-block;width:14px;height:14px;border:1.2px solid var(--ink);vertical-align:-2px;margin-right:6px}
.pt-info{border:1.5px solid var(--ink);background:#F7FAFC;padding:12px 16px;min-height:96px}
.pt-info .pt-name{font-weight:700;font-size:17px;text-transform:capitalize;display:flex;align-items:center;gap:10px}
.pt-info .pt-symbig{font-family:"Space Mono",monospace;font-size:22px;color:var(--charge)}
.pt-info .pt-tags{display:flex;gap:8px;flex-wrap:wrap;margin:8px 0}
.pt-info .tag{
  font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.08em;text-transform:uppercase;
  border:1.2px solid var(--rule);padding:3px 8px;color:var(--ink-soft);
}
.pt-info .tag.t-metal{background:#F5E27A;color:var(--ink);border-color:var(--ink)}
.pt-info .tag.t-non{background:#9FD0E8;color:var(--ink);border-color:var(--ink)}
.pt-info p{margin:0;font-size:14px}

/* particle-view readouts */
.pl-verdict{font-size:18px}
.pl-why{font-size:13px;margin:10px 0 0;color:var(--ink-soft)}

/* mixture builder chips */
.chipbank{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:14px}
.chip{
  display:flex;flex-direction:column;align-items:flex-start;gap:2px;
  font-family:"Spline Sans",system-ui,sans-serif;font-size:13px;text-transform:none;letter-spacing:0;
  padding:7px 12px;min-height:40px;border:1.5px solid var(--ink);background:#FFF;cursor:pointer;
  box-shadow:none;color:var(--ink);
}
.chip small{font-family:"Space Mono",monospace;font-size:9px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-soft)}
.chip-e{border-left:6px solid #2E7A8C}
.chip-c{border-left:6px solid #D93F2B}
.chip[aria-pressed="true"]{background:rgba(240,135,30,.16);outline:2px solid var(--charge);outline-offset:-2px}
.ml-kind{font-size:15px}

/* dissolving lab controls */
.dl-ctl{display:grid;grid-template-columns:repeat(auto-fit,minmax(170px,1fr));gap:14px;margin-bottom:12px}
.dl-ctl label{display:block;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft);margin-bottom:6px}
.dl-ctl select{width:100%;min-height:40px;border:1.5px solid var(--ink);background:#FFF;padding:6px 8px;font-family:"Spline Sans",system-ui,sans-serif;font-size:14px}
.dl-ctl input[type=range]{width:100%}
.dl-ctl .dl-tempv{font-family:"Space Mono",monospace;font-size:13px;font-weight:700}

/* comparison strip (three-way tables) */
table.cmp td{vertical-align:top;padding:8px 10px}
table.cmp td.h{font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;text-transform:uppercase;color:var(--ink-soft)}
.yes{color:#2E7A8C;font-weight:700}.no{color:#D93F2B;font-weight:700}

/* ============================================================
   Chemistry: Separation techniques (Chapter 4)
   ============================================================ */

/* separation planner */
.pn-grid{display:grid;grid-template-columns:1fr 1fr;gap:14px;margin-bottom:14px}
@media (max-width:620px){.pn-grid{grid-template-columns:1fr}}
.pn-box{border:1.5px solid var(--ink);background:#F7FAFC;padding:12px 14px;min-height:96px}
.pn-box h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--ink-soft);font-weight:400;
  display:flex;justify-content:space-between;gap:8px;align-items:baseline;
}
.pn-box h5 .pn-water{color:var(--charge)}
.pn-chip,.pn-got{
  display:inline-flex;align-items:center;gap:6px;font-size:13px;
  border:1.5px solid var(--ink);background:#FFF;padding:4px 9px;margin:0 6px 6px 0;
}
.pn-chip i{display:inline-block;width:12px;height:12px;border:1.2px solid var(--ink);flex:none}
.pn-chip small{font-family:"Space Mono",monospace;font-size:9px;letter-spacing:.06em;text-transform:uppercase;color:var(--ink-soft)}
.pn-got{border-color:var(--cool);background:rgba(46,122,140,.12);font-weight:600}
.pn-empty{font-size:13px;color:var(--ink-soft);font-style:italic}
.pn-act{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:14px}
.pn-act button{font-size:11px;padding:9px 12px;min-height:40px}
.pn-log{font-size:13px}
.pn-log ol{margin:0;padding-left:20px}
.pn-log li{margin-bottom:7px;line-height:1.55}
.pn-verdict{font-size:13px;border-top:1.5px dotted var(--rule);padding-top:10px;margin-top:4px}

/* filtration / evaporation / distillation readouts */
.sep-out{font-size:13px;margin:10px 0 0;color:var(--ink-soft)}
.sep-out strong{color:var(--ink)}

/* four national taps */
.wl-taps{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:8px;margin-bottom:10px}
.wl-steps{display:flex;gap:8px;flex-wrap:wrap;margin-bottom:14px}
.wl-btn{
  font-family:"Spline Sans",system-ui,sans-serif;font-size:13px;text-transform:none;letter-spacing:0;
  padding:10px 12px;min-height:44px;border:1.5px solid var(--ink);background:#FFF;cursor:pointer;
  box-shadow:none;color:var(--ink);text-align:left;
}
.wl-btn[aria-pressed="true"]{background:var(--ink);color:#F7FAFC}
.wl-step{border-left:5px solid var(--charge)}
.wl-panel{border:1.5px solid var(--ink);background:#F7FAFC;padding:14px 16px;min-height:120px}
.wl-panel h5{
  margin:0 0 8px;font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--charge);font-weight:400;
}
.wl-panel p{margin:0 0 8px;font-size:14px}
.wl-panel .wl-key{
  font-family:"Space Mono",monospace;font-size:11px;color:var(--ink-soft);
  border-top:1.5px dotted var(--rule);padding-top:8px;margin:10px 0 0;
}

/* technique decision table */
table.decide td{vertical-align:top;padding:9px 10px;font-size:14px}
table.decide .prop{font-weight:600}
table.decide .tech{font-family:"Space Mono",monospace;font-size:12px;color:var(--charge);font-weight:700}

/* ============================================================
   Physics: Ray Model of Light (Chapter 5)
   ============================================================ */
.lg-ctl{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:14px;margin-bottom:12px}
.lg-ctl label{display:block;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--ink-soft);margin-bottom:6px}
.lg-ctl input[type=range]{width:100%}
.lg-ctl b{font-family:"Space Mono",monospace;font-size:13px;color:var(--ink)}

/* concave / convex info panel */
.cv-body{display:grid;grid-template-columns:1fr 1fr;gap:16px;margin-top:14px}
@media (max-width:620px){.cv-body{grid-template-columns:1fr}}
.cv-facts{border:1.5px solid var(--ink);background:#F7FAFC;padding:12px 14px}
.cv-facts p{margin:0 0 8px;font-size:14px}
.cv-facts ul{margin:0;padding-left:18px;font-size:14px}
.cv-facts li{margin-bottom:6px}
.cv-tag{font-family:"Space Mono",monospace;font-size:11px;letter-spacing:.08em;text-transform:uppercase;
  color:var(--charge);display:block;margin-bottom:6px}

/* electromagnetic radiation panel */
.em-tabs{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:8px;margin-bottom:12px}
.em-btn{font-family:"Spline Sans",system-ui,sans-serif;font-size:14px;text-transform:none;letter-spacing:0;
  padding:11px 12px;min-height:44px;border:1.5px solid var(--ink);background:#FFF;cursor:pointer;
  box-shadow:none;color:var(--ink)}
.em-btn[aria-pressed="true"]{background:var(--ink);color:#F7FAFC}
.em-panel{border:1.5px solid var(--ink);background:#F7FAFC;padding:14px 18px}
.em-panel h5{margin:0 0 4px;font-family:"Space Mono",monospace;font-size:12px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--charge);font-weight:400}
.em-panel .em-vis{margin:0 0 12px;font-size:13px;color:var(--ink-soft);font-style:italic}
.em-panel h6{margin:12px 0 6px;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;
  text-transform:uppercase;font-weight:400}
.em-panel h6.em-good{color:var(--cool)}
.em-panel h6.em-bad{color:var(--hot)}
.em-panel ul{margin:0;padding-left:18px;font-size:14px}
.em-panel li{margin-bottom:7px;line-height:1.55}

/* image-characteristics readout */
.mi-list{margin:12px 0 0;padding-left:18px;font-size:14px}
.mi-list li{margin-bottom:6px}

/* ============================================================
   Chemistry: Atoms and Molecules (Chapter 8)
   ============================================================ */
.at-ctl{display:grid;grid-template-columns:repeat(auto-fit,minmax(190px,1fr));gap:14px;margin-bottom:12px}
.at-ctl label{display:block;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--ink-soft);margin-bottom:6px}
.at-ctl input[type=range]{width:100%}
.at-ctl b{font-family:"Space Mono",monospace;font-size:13px;color:var(--ink)}

/* scale-of-an-atom bar */
.sc-track{border:1.5px solid var(--ink);background:#FFF;height:26px;margin:12px 0 6px;position:relative;overflow:hidden}
.sc-bar{height:100%;background:var(--charge);transition:width .6s ease;min-width:2px}
.sc-title{font-size:17px;font-weight:700;margin:0}
.sc-dim{font-family:"Space Mono",monospace;font-size:12px;color:var(--ink-soft);margin:2px 0 8px}

/* atom builder readouts */
.ab-id{display:flex;align-items:center;gap:14px;border:1.5px solid var(--ink);background:#F7FAFC;padding:12px 16px;margin-bottom:12px}
.ab-sym{font-family:"Space Mono",monospace;font-size:32px;font-weight:700;color:var(--charge);line-height:1}
.ab-name{font-size:17px;text-transform:capitalize}
.ab-preset,.ml-preset{font-size:11px;padding:8px 11px;min-height:38px}

/* isotope tables */
table.isot{width:100%;border-collapse:collapse;margin:0}
table.isot td{border-bottom:1px dotted var(--rule);padding:8px 10px;font-size:14px}
table.isot td.h{font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;text-transform:uppercase;
  color:var(--ink-soft);border-bottom:1.5px solid var(--ink)}
table.isot .same{color:var(--ink-soft)}
table.isot .diff{color:var(--charge);font-weight:700}
.diff{color:var(--charge);font-weight:700}

/* relative atomic mass calculator */
.ram-row{display:flex;gap:10px;flex-wrap:wrap;align-items:stretch;margin-bottom:12px}
.ram-box{flex:1;min-width:130px;border:1.5px solid var(--ink);background:#F7FAFC;padding:10px 12px;text-align:center}
.ram-box .rl{display:block;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--ink-soft);margin-bottom:4px}
.ram-box .rv{font-family:"Space Mono",monospace;font-weight:700;font-size:16px}
.ram-work{font-family:"Space Mono",monospace;font-size:14px;border:1.5px solid var(--ink);background:#FFF;
  padding:12px 14px;margin-bottom:10px;overflow-x:auto;white-space:nowrap}
.ram-eq{display:flex;align-items:baseline;gap:10px;font-family:"Space Mono",monospace;margin-bottom:10px}
.ram-eq .lbl{font-size:11px;letter-spacing:.08em;text-transform:uppercase;color:var(--ink-soft)}
.ram-ans{font-size:26px;font-weight:700;color:var(--charge)}

/* molecule builder */
.ml-bank{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:12px;align-items:center}
.ml-add{font-family:"Space Mono",monospace;font-size:15px;font-weight:700;width:46px;height:46px;
  min-height:46px;padding:0;border:1.5px solid var(--ink);cursor:pointer;box-shadow:none}
.ml-formula{font-family:"Space Mono",monospace;font-size:24px;font-weight:700}
.ml-kind{font-size:14px;font-weight:700}
.fl-formula{font-family:"Space Mono",monospace;font-size:30px;font-weight:700;color:var(--charge);
  text-align:center;padding:10px 0 16px}
.fl-kind{font-size:15px;font-weight:700}

/* history-of-models panel */
.mh-figs{display:flex;justify-content:center;margin-bottom:12px}
.mh-panel,.at-panel{border:1.5px solid var(--ink);background:#F7FAFC;padding:14px 18px}
.mh-panel h5,.at-panel h5{margin:0 0 4px;font-family:"Space Mono",monospace;font-size:12px;letter-spacing:.1em;
  text-transform:uppercase;color:var(--charge);font-weight:400}
.mh-who{margin:0 0 12px;font-size:13px;color:var(--ink-soft);font-style:italic}
.mh-panel h6,.at-panel h6{margin:12px 0 5px;font-family:"Space Mono",monospace;font-size:10px;
  letter-spacing:.1em;text-transform:uppercase;font-weight:400}
.mh-good,.at-good{color:var(--cool)}
.mh-bad,.at-bad{color:var(--hot)}
.mh-panel p{margin:0;font-size:14px;line-height:1.6}
.at-panel ul{margin:0;padding-left:18px;font-size:14px}
.at-panel li{margin-bottom:7px;line-height:1.55}
.at-tabs,.mh-tabs{display:grid;grid-template-columns:repeat(auto-fit,minmax(140px,1fr));gap:8px;margin-bottom:12px}
.at-btn,.mh-btn{font-family:"Spline Sans",system-ui,sans-serif;font-size:14px;text-transform:none;letter-spacing:0;
  padding:11px 12px;min-height:44px;border:1.5px solid var(--ink);background:#FFF;cursor:pointer;
  box-shadow:none;color:var(--ink)}
.at-btn[aria-pressed="true"],.mh-btn[aria-pressed="true"]{background:var(--ink);color:#F7FAFC}

/* ---- Challenging Qns Lvl 2 header treatment ----------------- */
.lvl2-note{
  border:1.5px solid var(--charge);background:rgba(240,135,30,.08);
  padding:14px 18px;margin:0 0 22px;font-size:14px;
}
.lvl2-note strong{color:var(--ink)}
.lvl2-note .lvl2-tag{
  display:block;font-family:"Space Mono",monospace;font-size:10px;letter-spacing:.12em;
  text-transform:uppercase;color:var(--charge);margin-bottom:6px;
}