/* =========================================================
   Acids, Bases & pH — stylesheet

   This is CHM/01 in the Science Simulations collection: an extension of
   the school-laboratory-instrument world established by The Interactive
   Heart, not a new one. Case, panel, ink, screen and amber/lamp tokens
   below are taken verbatim from the collection's live CSS (board.css) —
   see this folder's DESIGN.md for why the values differ from the Heart's
   own DESIGN.md prose. What is new here is the pH/indicator spectrum
   (this simulation's specimen) and the components a chemistry bench
   needs that a cardiovascular one did not: pH scale, particle box,
   burette + titration trace, reaction bench, oxide sorter, salt flow.
   ========================================================= */

:root{
  --fascia:#1b2c48;
  --fascia-hi:#2b4066;
  --fascia-lo:#121f34;
  --fascia-ink:#f2efe6;
  --fascia-ink-2:#a9b8cf;

  --panel:#d5d2c4;
  --panel-hi:#e6e3d5;
  --panel-lo:#c6c3b4;
  --panel-edge:#f2efe2;
  --card:#efeade;
  --chassis:#131f33;
  --chassis-dk:#0c1524;

  --ink:#1e201c;
  --ink-2:#46483f;
  --rule:#a9a79c;
  --rule-dk:#8e8c82;

  --screen:#0d1420;
  --screen-2:#151f31;
  --screen-ink:#dfe6f0;
  --screen-ink-2:#9fb0c6;
  --graticule:rgba(255,183,51,.13);
  --graticule-mj:rgba(255,183,51,.26);

  --amber:#6f4708;
  --amber-lit:#e8a63a;
  --lamp-lit:#ffb733;
  --lamp-off:#7e8079;
  --trace:#ffb733;

  /* the specimen: pH 1 / pH 7 / pH 13 as fixed reference points for CSS
     that cannot call ABData.colourForPH() — the scale itself is drawn
     from the full JS gradient */
  --ph-acid:#c0272d;
  --ph-neutral:#3f9e4f;
  --ph-alkali:#2166c4;

  --fs-display:clamp(1.5rem, 2.6vw, 2.15rem);
  --fs-legend-sm:.64rem;
  --fs-legend:.72rem;
  --fs-legend-lg:.80rem;
  --fs-body-sm:.82rem;
  --fs-body:.90rem;
  --fs-body-lg:.98rem;
  --fs-title:1.08rem;
  --fs-title-lg:1.24rem;
  --fs-data:1rem;
  --fs-data-lg:1.85rem;
  --fs-data-xl:3rem;

  --r:3px;
  --r-well:4px;
  --r-screen:2px;

  --edge-hi:rgba(255,255,255,.38);
  --edge-lo:rgba(0,0,0,.18);
  --recess-deep:rgba(0,0,0,.55);
  --lamp-seat:rgba(0,0,0,.48);

  --proud:inset 0 1px 0 var(--panel-edge), 0 1px 0 rgba(0,0,0,.30);
  --pressed:inset 0 1px 2px rgba(0,0,0,.34);
  --well:inset 0 1px 2px rgba(0,0,0,.28), inset 0 -1px 0 var(--panel-edge);
  --bezel:inset 0 2px 5px var(--recess-deep);
  --flush:inset 0 1px 0 var(--edge-hi);
  --raised:inset 0 1px 0 var(--edge-hi), 0 1px 0 var(--edge-lo);
  --seated:inset 0 1px 2px var(--lamp-seat);

  --font-legend:"Arial Narrow","Roboto Condensed","Liberation Sans Narrow","Nimbus Sans Narrow",Arial,system-ui,sans-serif;
  --font-data:ui-monospace,"Cascadia Mono","Segoe UI Mono",Menlo,Consolas,"DejaVu Sans Mono",monospace;
  --font-read:"Iowan Old Style",Charter,"Bitstream Charter",Georgia,"Times New Roman",serif;

  --focus:#1e201c;
}

*{box-sizing:border-box}
html,body{height:100%}
/* The reading window sizes its viewBox from its own rendered width, so the page
   width has to be stable: without this a tall composition summons a scrollbar,
   which narrows the window *after* its viewBox was computed, and the two can
   chase each other. Reserving the gutter removes the feedback loop entirely. */
html{scroll-behavior:smooth; scrollbar-gutter:stable}
body{
  margin:0; min-height:100%;
  font-family:var(--font-read); font-size:16px;
  color:var(--fascia-ink); background:var(--fascia);
  -webkit-font-smoothing:antialiased;
}

.legend,.stat-label,.quick-title,.next-title,.block-title,.q-kicker,.info-eyebrow,
.slider-label,.vpill,.fill,.tab,.chip,.vbtn,.btn,.opt,.quiz-score,.round-num,.ord,
.rack-note,.bin-title,.route-title,.flow-title,.eq-kicker,.mix-note{
  font-family:var(--font-legend);
}
.stat-val,.big,.big-total,.phase-no,.ord,.quiz-score,.tab-no,.data,.round-num,
.ph-readout,.vol-readout,.eq-line{
  font-family:var(--font-data);
  font-variant-numeric:tabular-nums;
  font-feature-settings:"tnum" 1;
}

:where(button,[href],input,select,textarea,[tabindex]):focus-visible{
  outline:3px solid var(--focus); outline-offset:2px;
}
/* The ring is drawn outside the control, so on the navy case the near-black
   --focus landed at 1.17:1 and was effectively invisible — the whole top rail
   had no usable focus indicator. Amber is the instrument's attention register
   and clears 6.3:1 on the case, so controls mounted on it get that instead. */
.tab:focus-visible,
.chip:focus-visible,
.skip-link:focus-visible{outline-color:var(--amber-lit)}
.sr-only{
  position:absolute; width:1px; height:1px; padding:0; margin:-1px;
  overflow:hidden; clip:rect(0 0 0 0); white-space:nowrap; border:0;
}
.skip-link{
  position:absolute; left:-9999px; top:0; z-index:100;
  background:var(--ink); color:var(--panel); padding:10px 16px;
  font-family:var(--font-legend); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
}
.skip-link:focus{left:0}
.noscript-note{
  margin:0; padding:14px 20px; text-align:center;
  background:var(--amber-lit); color:var(--ink);
  font-family:var(--font-legend); font-weight:700; letter-spacing:.04em;
}

/* =========================================================
   TOP RAIL
   ========================================================= */
.topbar{
  display:flex; align-items:stretch; gap:18px; flex-wrap:wrap;
  max-width:1760px; margin:0 auto; padding:12px 20px;
  background:var(--fascia); border-bottom:1px solid var(--chassis-dk);
  box-shadow:inset 0 1px 0 var(--fascia-hi), 0 1px 0 rgba(0,0,0,.30);
  position:sticky; top:0; z-index:40;
}
.mark{flex:0 0 auto; width:19px; height:19px; display:block}
.mark circle,.mark path{fill:none; stroke:currentColor; stroke-width:1.5; stroke-linecap:round; stroke-linejoin:round}
.brand .mark{color:var(--amber-lit)}

.brand{
  display:flex; align-items:center; gap:9px; min-width:0;
  background:var(--panel); color:var(--ink);
  border:1px solid var(--rule-dk); border-radius:var(--r); box-shadow:var(--well);
  padding:7px 13px 7px 11px;
}
.brand-mark{
  position:relative; flex:0 0 auto; width:16px; height:16px; border-radius:50%;
  background:var(--lamp-off); box-shadow:var(--seated); border:1px solid var(--chassis-dk);
}
.brand-mark.lit{
  animation:lamp-pulse 1.6s ease-in-out infinite;
}
/* a lub-dub, then a rest — the same rhythm the Interactive Heart's own
   identity lamp keeps time to, carried here rather than left steady */
@keyframes lamp-pulse{
  0%,100%{background:var(--lamp-off); box-shadow:var(--seated)}
  8%,20%{background:var(--lamp-lit); box-shadow:inset 0 1px 1px rgba(255,255,255,.4), 0 0 4px var(--lamp-lit)}
  30%{background:var(--lamp-off); box-shadow:var(--seated)}
  38%,50%{background:var(--lamp-lit); box-shadow:inset 0 1px 1px rgba(255,255,255,.4), 0 0 4px var(--lamp-lit)}
  60%{background:var(--lamp-off); box-shadow:var(--seated)}
}
.brand-text{display:flex; flex-direction:column; line-height:1.15; min-width:0}
.brand-text strong{
  font-family:var(--font-legend); font-size:var(--fs-body-lg); font-weight:700;
  text-transform:uppercase; letter-spacing:.09em; color:var(--ink);
}
.brand-text small{
  font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700;
  text-transform:uppercase; letter-spacing:.10em; color:var(--ink-2);
}
.brand-text small i{
  font-family:var(--font-read); font-style:italic; text-transform:none;
  letter-spacing:.01em; font-weight:400; font-size:1.12em; color:var(--amber);
}

.tabs{display:flex; gap:5px; flex:1; flex-wrap:wrap; justify-content:center; align-items:center}
.tab{
  appearance:none; cursor:pointer; position:relative;
  display:flex; align-items:center; gap:8px;
  min-height:42px; padding:9px 13px 9px 10px;
  background:var(--panel); color:var(--ink-2);
  border:1px solid var(--rule-dk); border-radius:var(--r);
  font-size:var(--fs-legend-lg); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
  box-shadow:var(--flush);
  transition:background .12s, color .12s, box-shadow .12s;
}
.tab-no{
  flex:0 0 auto; width:17px; height:17px; border-radius:50%;
  display:grid; place-items:center;
  background:var(--chassis-dk); color:var(--panel-edge);
  border:1px solid #2b2a26; box-shadow:var(--seated);
  font-size:var(--fs-legend-sm); font-weight:700; line-height:1;
}
.tab:hover{background:var(--panel-hi); color:var(--ink)}
.tab:active{box-shadow:var(--pressed)}
.tab.is-active{background:var(--panel-hi); color:var(--ink); border-color:var(--chassis); box-shadow:var(--proud)}
.tab.is-active .tab-no{background:var(--lamp-lit); color:#2e1c02; box-shadow:inset 0 1px 1px rgba(255,255,255,.45), 0 0 4px var(--lamp-lit)}

.topbar-tools{display:flex; gap:5px; align-items:center}
.chip{
  appearance:none; cursor:pointer; min-height:36px; padding:8px 13px;
  font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
  color:var(--ink-2); background:var(--panel);
  border:1px solid var(--rule-dk); border-radius:var(--r); box-shadow:var(--flush);
  transition:background .12s, color .12s, box-shadow .12s;
}
.chip:hover{background:var(--panel-hi); color:var(--ink)}
.chip:active{box-shadow:var(--pressed)}
.chip[aria-pressed="true"]{background:var(--panel-hi); color:var(--ink); border-color:var(--chassis); box-shadow:var(--proud)}
.chip[aria-pressed]::before{
  content:""; display:inline-block; vertical-align:1px;
  width:7px; height:7px; margin-right:7px; border-radius:50%;
  background:var(--lamp-off); border:1px solid var(--chassis-dk);
}
.chip[aria-pressed="true"]::before{background:var(--lamp-lit); border-color:#8a5f14; box-shadow:0 0 4px var(--lamp-lit)}

/* =========================================================
   LAYOUT
   ========================================================= */
.layout{
  display:grid; grid-template-columns:minmax(0,1fr) 420px;
  gap:14px; padding:20px; align-items:start;
  max-width:1720px; margin:0 auto;
}

/* =========================================================
   READING WINDOW
   ========================================================= */
.stage{
  background:var(--panel); color:var(--ink);
  border:1px solid var(--chassis-dk); border-radius:var(--r);
  box-shadow:inset 0 1px 0 var(--panel-edge), 0 1px 0 var(--fascia-hi);
  padding:14px; min-width:0; scroll-margin-top:84px;
}
.stage-head{display:flex; align-items:flex-end; gap:16px; flex-wrap:wrap; justify-content:space-between; padding:0 2px 12px}
.stage-head-text{min-width:0}
.stage-head h1{
  margin:0; font-family:var(--font-legend);
  font-size:var(--fs-display); font-weight:700; line-height:1.05;
  text-transform:uppercase; letter-spacing:.02em; color:var(--ink);
}
.stage-head p{margin:4px 0 0; font-family:var(--font-read); color:var(--ink-2); font-size:var(--fs-body); line-height:1.5; max-width:62ch}

.viewswitch{display:flex; gap:5px; flex-wrap:wrap}
.vbtn{
  appearance:none; cursor:pointer; min-height:38px; padding:8px 15px;
  font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
  color:var(--ink-2); background:var(--panel);
  border:1px solid var(--rule-dk); border-radius:var(--r); box-shadow:var(--flush);
  transition:background .12s, color .12s, box-shadow .12s;
}
.vbtn:hover{background:var(--panel-hi); color:var(--ink)}
.vbtn:active{box-shadow:var(--pressed)}
.vbtn.is-active{background:var(--panel-hi); color:var(--ink); border-color:var(--chassis); box-shadow:var(--proud)}

.svg-wrap{
  position:relative; width:100%; background:var(--screen);
  border:8px solid var(--chassis-dk); border-radius:var(--r-screen);
  box-shadow:var(--bezel), 0 1px 0 var(--panel-edge);
}
.svg-wrap::after{content:""; position:absolute; inset:0; pointer-events:none; box-shadow:inset 0 0 0 1px rgba(223,230,240,.10)}
.svg-wrap.hidden{display:none}

.window-plate{
  position:absolute; z-index:2; left:0; right:0; bottom:-7px; margin:0;
  display:flex; gap:14px; justify-content:space-between; align-items:baseline;
  padding:0 4px; pointer-events:none;
  font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700;
  text-transform:uppercase; letter-spacing:.11em; color:var(--fascia-ink-2);
}
.window-plate span:first-child{font-family:var(--font-data); color:var(--fascia-ink)}

#bench-view{width:100%; height:auto; display:block; max-height:74vh; touch-action:manipulation}

/* =========================================================
   THE READING WINDOW'S OWN TYPE — screened caps for titles and
   captions, tabular data for anything measured, exactly the three
   registers the panel uses, just rendered as SVG text
   ========================================================= */
/* The window's viewBox width tracks its rendered width (ABData.metrics), so one
   viewBox unit is one CSS pixel and these sizes are what actually renders — at
   every viewport. Previously the box was a fixed 1000 units and its type scaled
   with the container, which meant 4.1px captions on a phone and 8.9px in the
   two-column desktop layout at 1200px, where the window collapses to ~682px.
   Scaling the type up instead was measured and capped out at +15% before
   captions collided, so the compositions reflow against the width instead. */
.scope-ink text{font-family:var(--font-legend)}
.scope-title{font-size:22px; font-weight:700; letter-spacing:.02em; text-transform:uppercase; fill:var(--screen-ink)}
.scope-cap{font-family:var(--font-read); font-size:15px; fill:var(--screen-ink-2)}
.scope-cap2{font-family:var(--font-read); font-size:13px; fill:var(--screen-ink-2)}
.scope-readout{font-family:var(--font-data); font-size:26px; font-weight:600; fill:var(--trace)}
.scope-num{font-family:var(--font-data); font-size:13px; fill:var(--screen-ink-2)}
.scope-ion{font-family:var(--font-data); font-size:13px; font-weight:700; fill:#2e1c02}
.scope-ion-sm{font-family:var(--font-data); font-size:11px; font-weight:700; fill:#dfe6f0}
/* the anion sits on a light blue disc, so it takes dark ink the same way H⁺
   takes dark ink on amber — pale ink measured 2.18:1 there */
.scope-ion-anion{font-family:var(--font-data); font-size:11px; font-weight:700; fill:#0d2038}
.scope-lbl{font-family:var(--font-legend); font-size:13px; font-weight:700; text-transform:uppercase; letter-spacing:.06em; fill:var(--screen-ink-2)}
.scope-lbl-lit{fill:var(--amber-lit)}

.stage-foot{
  display:flex; justify-content:space-between; align-items:flex-start; gap:20px; flex-wrap:wrap;
  margin-top:12px; padding-top:11px; border-top:1px solid var(--rule);
}
.key{display:flex; gap:24px; flex-wrap:wrap}
.key-item{
  display:flex; align-items:flex-start; gap:9px;
  font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
  color:var(--ink); line-height:1.35;
}
.key-item em{
  display:block; margin-top:3px; font-family:var(--font-read); font-style:normal;
  text-transform:none; letter-spacing:0; font-weight:400; font-size:var(--fs-legend-lg); color:var(--ink-2);
}
.dot{
  flex:0 0 auto; width:18px; height:18px; border-radius:50%; display:inline-block; margin-top:-1px;
  border:1px solid var(--chassis-dk);
  box-shadow:inset 0 1px 1px rgba(255,255,255,.45), inset 0 -2px 3px rgba(0,0,0,.35);
}
.orient-note{margin:0; font-family:var(--font-read); font-size:var(--fs-legend-lg); line-height:1.55; color:var(--ink-2); max-width:46ch; text-align:right}
.orient-note strong{color:var(--ink); font-weight:700}

/* =========================================================
   THE WORKING COLUMN
   ========================================================= */
.panel{
  background:var(--panel); color:var(--ink);
  border:1px solid var(--chassis-dk); border-radius:var(--r);
  box-shadow:inset 0 1px 0 var(--panel-edge), 0 1px 0 var(--fascia-hi);
  padding:14px; min-height:520px; position:sticky; top:82px;
  max-height:calc(100vh - 96px); overflow-y:auto;
  scrollbar-width:thin; scrollbar-color:var(--chassis) var(--panel-lo);
}
.panel::-webkit-scrollbar{width:11px}
.panel::-webkit-scrollbar-track{background:var(--panel-lo)}
.panel::-webkit-scrollbar-thumb{background:var(--chassis); border:2px solid var(--panel-lo)}

.pane{display:none}
.pane.is-active{display:block}

.pane-title{margin:0 0 3px; font-family:var(--font-legend); font-size:var(--fs-title); font-weight:700; text-transform:uppercase; letter-spacing:.07em; color:var(--ink)}
.pane-lead{margin:0 0 16px; font-family:var(--font-read); color:var(--ink-2); font-size:var(--fs-body); line-height:1.6; max-width:64ch}
.pane-lead strong,.pane-lead b{color:var(--ink)}
.pane-note{font-family:var(--font-read); color:var(--ink-2); font-size:var(--fs-body-sm); line-height:1.6}

.block{margin-bottom:12px}
.control-block{background:var(--panel-lo); border-radius:var(--r-well); box-shadow:var(--well); padding:13px 13px 14px; margin-bottom:12px}
.block-title{margin:0 0 3px; font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.09em; color:var(--ink)}
.block-note{margin:0 0 11px; font-family:var(--font-read); font-size:var(--fs-body-sm); color:var(--ink-2); line-height:1.55}
.block-note b{color:var(--ink)}

.info-card{background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r); box-shadow:0 1px 0 var(--panel-edge); padding:15px 16px 16px}
.info-eyebrow{margin:0 0 8px; padding-bottom:7px; border-bottom:1px solid var(--rule); font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.11em; color:var(--ink-2)}
.info-title{margin:0 0 3px; font-family:var(--font-legend); font-size:var(--fs-title-lg); font-weight:700; line-height:1.15; text-transform:uppercase; letter-spacing:.045em; color:var(--ink)}
.info-tagline{margin:0 0 13px; font-family:var(--font-read); font-style:italic; color:var(--ink-2); font-size:var(--fs-body); line-height:1.4}
.info-lead{margin:0 0 12px; font-size:var(--fs-body-lg); line-height:1.62; color:var(--ink)}
.info-body{margin:0 0 14px; font-size:var(--fs-body); line-height:1.68; color:var(--ink-2)}
.info-lead b,.info-body b{color:var(--ink); font-weight:700}

.badge-row{display:flex; gap:7px; flex-wrap:wrap; margin:0 0 13px}
.badge{
  font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700;
  text-transform:uppercase; letter-spacing:.08em;
  padding:4px 9px; border:1px solid var(--rule-dk); border-radius:var(--r);
  color:var(--ink); background:transparent; display:inline-flex; align-items:center; gap:6px;
}
.badge::before{content:""; width:8px; height:8px; border-radius:50%; border:1px solid var(--chassis-dk)}
.badge-acid::before{background:var(--ph-acid)}
.badge-alkali::before{background:var(--ph-alkali)}
.badge-neutral::before{background:var(--ph-neutral)}
.badge-group{background:var(--panel-lo)}
.badge-group::before{display:none}

.fact-box{margin:0 0 14px; padding:11px 0 0; border-top:1px solid var(--rule)}
.fact-box h4{margin:0 0 7px; font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700; text-transform:uppercase; letter-spacing:.11em; color:var(--amber)}
.fact-box ul{margin:0; padding:0; list-style:none}
.fact-box li{position:relative; padding-left:15px; margin-bottom:6px; font-size:var(--fs-body-sm); line-height:1.6; color:var(--ink-2)}
.fact-box li::before{content:""; position:absolute; left:0; top:.62em; width:6px; height:1px; background:var(--amber)}

.hint-list{margin:0 0 16px; padding-left:18px}
.hint-list li{font-size:var(--fs-body); line-height:1.62; color:var(--ink-2); margin-bottom:6px}
.hint-list strong{color:var(--ink)}

.quick-title,.next-title{margin:0 0 8px; font-size:var(--fs-legend-sm); font-weight:700; text-transform:uppercase; letter-spacing:.11em; color:var(--ink-2)}
.quick-row,.linked{display:flex; flex-wrap:wrap; gap:5px}
.quick{
  appearance:none; cursor:pointer; font-family:var(--font-legend); font-size:var(--fs-legend); font-weight:700;
  text-transform:uppercase; letter-spacing:.06em;
  background:var(--panel); border:1px solid var(--rule-dk); color:var(--ink);
  border-radius:var(--r); padding:7px 10px; min-height:30px; box-shadow:var(--flush);
  transition:background .12s, box-shadow .12s;
}
.quick:hover{background:var(--panel-hi)}
.quick:active{box-shadow:var(--pressed)}

.route{margin:14px 0 0; padding:11px 0 0; border-top:1px solid var(--rule); font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.6; color:var(--ink-2)}
.route b{color:var(--ink)}
.route-steps{display:flex; flex-wrap:wrap; gap:5px; margin-top:9px}

/* =========================================================
   CONTROLS
   ========================================================= */
.btn-row{display:flex; gap:6px; flex-wrap:wrap; margin-bottom:10px}
.btn{
  appearance:none; cursor:pointer; font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.07em;
  background:var(--panel); color:var(--ink); border:1px solid var(--rule-dk); border-radius:var(--r);
  padding:10px 14px; min-height:38px; flex:0 0 auto; box-shadow:var(--raised);
  transition:background .12s, box-shadow .12s;
}
.btn:hover{background:var(--panel-hi)}
.btn:active{box-shadow:var(--pressed)}
.btn:disabled{opacity:.45; cursor:not-allowed; box-shadow:var(--pressed)}
.btn-primary{background:var(--panel-hi); border-color:var(--chassis); box-shadow:var(--proud)}
.btn-primary:hover{background:var(--panel-edge)}
.btn-primary:active{box-shadow:var(--pressed)}
.btn-small{padding:8px 11px; min-height:32px; font-size:var(--fs-legend)}
.btn-ghost{background:transparent; box-shadow:none; border-color:var(--rule)}
.btn-ghost:hover{background:var(--panel)}
.btn-wide{width:100%; justify-content:center; text-align:center}

.slider-label{
  display:flex; justify-content:space-between; align-items:baseline; gap:10px;
  font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.08em;
  color:var(--ink); margin-bottom:8px;
}
.slider-label output{
  font-family:var(--font-data); font-size:var(--fs-legend-lg); font-weight:700;
  text-transform:none; letter-spacing:0; color:var(--ink);
  background:var(--card); border:1px solid var(--rule-dk); padding:2px 7px; border-radius:2px;
}
input[type=range]{-webkit-appearance:none; appearance:none; width:100%; height:20px; background:transparent; outline:none; margin:0 0 2px}
input[type=range]::-webkit-slider-runnable-track{height:6px; border-radius:2px; background:var(--chassis-dk); box-shadow:var(--seated), 0 1px 0 var(--panel-edge)}
input[type=range]::-moz-range-track{height:6px; border-radius:2px; background:var(--chassis-dk); box-shadow:var(--seated), 0 1px 0 var(--panel-edge)}
input[type=range]::-webkit-slider-thumb{
  -webkit-appearance:none; width:14px; height:22px; margin-top:-8px; border-radius:2px; cursor:pointer;
  background:linear-gradient(var(--panel-edge) 0 45%, var(--panel-lo) 55% 100%);
  border:1px solid var(--chassis-dk); box-shadow:0 1px 2px rgba(0,0,0,.4);
}
input[type=range]::-moz-range-thumb{
  width:14px; height:22px; border-radius:2px; cursor:pointer;
  background:linear-gradient(var(--panel-edge) 0 45%, var(--panel-lo) 55% 100%);
  border:1px solid var(--chassis-dk); box-shadow:0 1px 2px rgba(0,0,0,.4);
}
.scale{display:flex; justify-content:space-between; margin:1px 0 0; padding:0 1px; font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700; text-transform:uppercase; letter-spacing:.06em; color:var(--ink-2)}

.select-row{display:flex; flex-wrap:wrap; gap:5px; margin-bottom:4px}
.select-chip{
  appearance:none; cursor:pointer; flex:1 1 auto; text-align:left;
  font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.4;
  background:var(--panel); border:1px solid var(--rule-dk); color:var(--ink);
  border-radius:var(--r); padding:9px 11px; box-shadow:var(--flush);
  transition:background .12s, box-shadow .12s;
}
.select-chip:hover{background:var(--panel-hi)}
.select-chip.is-active{background:var(--panel-hi); border-color:var(--chassis); box-shadow:var(--proud)}
.select-chip b{display:block; font-family:var(--font-legend); font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--ink)}
.select-chip span{color:var(--ink-2)}

select.field{
  width:100%; padding:9px 10px; min-height:38px;
  font-family:var(--font-read); font-size:var(--fs-body); color:var(--ink);
  background:var(--card); border:1px solid var(--chassis); border-radius:2px; box-shadow:var(--pressed);
}

.result-line{margin:10px 0 0; font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.6; color:var(--ink); min-height:1.2em}
.result-line b{font-weight:700}
.result-line.is-hint{color:var(--amber)}

/* =========================================================
   INDICATOR BENCH — the rack, the tube, the pH scale
   ========================================================= */
.rack-list{list-style:none; margin:0; padding:0; display:flex; flex-direction:column; gap:4px}
.rack-item{
  appearance:none; cursor:pointer; width:100%; text-align:left;
  display:flex; align-items:center; gap:9px;
  background:var(--panel); border:1px solid var(--rule-dk); border-radius:var(--r);
  padding:9px 10px; box-shadow:var(--flush);
  font-family:var(--font-read); font-size:var(--fs-body-sm); color:var(--ink);
  transition:background .12s, box-shadow .12s;
}
.rack-item:hover{background:var(--panel-hi)}
.rack-item.is-active{background:var(--panel-hi); border-color:var(--chassis); box-shadow:var(--proud)}
.rack-swatch{flex:0 0 auto; width:16px; height:16px; border-radius:50%; border:1px solid var(--chassis-dk); box-shadow:inset 0 1px 1px rgba(255,255,255,.35)}
/* an untested substance shows an empty socket, so the rack records what you
   have done rather than previewing every answer before you start */
.rack-swatch.is-untested{
  background:var(--panel-lo);
  box-shadow:inset 0 1px 2px rgba(0,0,0,.38);
  border-color:var(--rule-dk);
}
.rack-note{display:block; margin:2px 0 0; font-size:var(--fs-legend-sm); color:var(--ink-2); text-transform:none; letter-spacing:0}

.ph-readout{font-size:var(--fs-data-lg); font-weight:600; color:var(--trace); text-shadow:0 0 6px rgba(255,183,51,.35)}

/* the pH scale ticks/numerals drawn inside the reading window svg reuse
   the scope's screen-ink values via inline fill, not separate classes */

/* =========================================================
   PARTICLE BOX — strength vs concentration
   ========================================================= */
.acid-picker{display:flex; flex-direction:column; gap:5px; margin-bottom:11px}

/* =========================================================
   TITRATION BENCH
   ========================================================= */
.indicator-row{display:flex; flex-wrap:wrap; gap:5px; margin-bottom:4px}
.eq-kicker{margin:11px 0 4px; font-size:var(--fs-legend-sm); font-weight:700; text-transform:uppercase; letter-spacing:.1em; color:var(--ink-2)}
.eq-line{display:block; font-size:var(--fs-body); color:var(--ink); background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r); padding:9px 11px; margin-bottom:6px; line-height:1.5}
.vol-readout{font-size:var(--fs-data-lg); font-weight:600; color:var(--ink)}

/* =========================================================
   REACTION BENCH
   ========================================================= */
.mix-note{margin:9px 0 0; padding:9px 10px; background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r); font-size:var(--fs-body-sm); line-height:1.55; color:var(--ink); text-transform:none; letter-spacing:0; font-family:var(--font-read)}

/* oxide sorter */
.oxide-tray{display:flex; flex-wrap:wrap; gap:6px; margin-bottom:11px}
.oxide-card{
  appearance:none; cursor:pointer; flex:0 0 auto;
  background:var(--panel); border:1px solid var(--rule-dk); border-radius:var(--r);
  padding:9px 12px; min-width:64px; text-align:center; box-shadow:var(--raised);
  font-family:var(--font-data); font-size:var(--fs-body-lg); font-weight:600; color:var(--ink);
  transition:background .12s, box-shadow .12s, opacity .15s;
}
.oxide-card small{display:block; font-family:var(--font-legend); font-size:var(--fs-legend-sm); font-weight:700; text-transform:none; letter-spacing:0; color:var(--ink-2); margin-top:2px}
.oxide-card:hover{background:var(--panel-hi)}
.oxide-card.is-picked{background:var(--panel-hi); border-color:var(--chassis); box-shadow:var(--proud)}
.oxide-card.is-placed{opacity:.4; cursor:default}
/* got wrong at least once and still unplaced — amber is the panel's attention
   register, and a hairline underline carries it without a second colour */
.oxide-card.is-tried{border-color:var(--amber); box-shadow:var(--raised), inset 0 -2px 0 var(--amber-lit)}
.bin-grid{display:grid; grid-template-columns:1fr 1fr; gap:6px}
.bin{
  appearance:none; cursor:pointer; text-align:left;
  background:var(--panel-lo); border:1px solid var(--rule-dk); border-radius:var(--r-well);
  padding:9px 10px; box-shadow:var(--well); min-height:64px;
  transition:background .15s, box-shadow .15s;
}
.bin-title{display:block; font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.06em; color:var(--ink); margin-bottom:3px}
.bin-note{display:block; font-family:var(--font-read); font-size:var(--fs-legend-lg); color:var(--ink-2); line-height:1.35}
.bin-contents{display:flex; flex-wrap:wrap; gap:3px; margin-top:6px}
.bin-contents span{font-family:var(--font-data); font-size:var(--fs-legend); background:var(--card); border:1px solid var(--rule-dk); padding:1px 5px; border-radius:2px}
.bin.flash-good{background:var(--panel-hi); box-shadow:var(--proud), 0 0 0 1px #8a5f14}
.bin.flash-bad{box-shadow:var(--well), 0 0 0 1px var(--amber)}

/* salt-preparation flowchart */
.flow-list{margin:0; padding-left:0; list-style:none; counter-reset:seq}
.flow-list li{
  counter-increment:seq; position:relative; padding-left:24px;
  font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.5;
  color:var(--ink-2); margin-bottom:8px;
}
.flow-list li::before{
  content:counter(seq); position:absolute; left:0; top:1px; width:16px; height:16px; border-radius:50%;
  display:grid; place-items:center; font-family:var(--font-data); font-size:var(--fs-legend-sm); font-weight:700;
  background:var(--panel); color:var(--ink-2); border:1px solid var(--rule-dk);
}
.flow-list li.is-done{color:var(--ink)}
.flow-list li.is-done::before{background:var(--lamp-lit); color:#2e1c02; border-color:#8a5f14; box-shadow:0 0 4px var(--lamp-lit)}
.flow-title{margin:12px 0 4px; font-size:var(--fs-legend); font-weight:700; text-transform:uppercase; letter-spacing:.08em; color:var(--ink)}
.route-title{
  display:block; margin:11px 0 8px; padding:9px 11px; text-align:center;
  background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r);
  font-size:var(--fs-body-lg); font-weight:700; text-transform:uppercase; letter-spacing:.03em; color:var(--ink);
}

/* =========================================================
   QUIZ — inherited component family, colours generalised
   ========================================================= */
.quiz-intro h2{margin:0 0 4px; font-family:var(--font-legend); font-size:var(--fs-title); font-weight:700; text-transform:uppercase; letter-spacing:.07em; color:var(--ink)}
.round-card{
  display:flex; gap:11px; align-items:flex-start; text-align:left; width:100%;
  background:var(--panel); border:1px solid var(--rule-dk); border-radius:var(--r);
  padding:12px; margin-bottom:7px; cursor:pointer; color:inherit; box-shadow:var(--raised);
  transition:background .12s, box-shadow .12s;
}
.round-card:hover{background:var(--panel-hi)}
.round-card:active{box-shadow:var(--pressed)}
.round-num{
  flex:0 0 28px; height:28px; display:grid; place-items:center; border-radius:50%;
  background:var(--chassis-dk); color:var(--panel-edge); border:1px solid #2b2a26; box-shadow:var(--seated);
  font-size:var(--fs-legend-lg); font-weight:700;
}
.round-card h3{margin:0 0 3px; font-family:var(--font-legend); font-size:var(--fs-body); font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--ink)}
.round-card p{margin:0; font-family:var(--font-read); font-size:var(--fs-body-sm); color:var(--ink-2); line-height:1.5}

.quiz-bar{display:flex; justify-content:space-between; align-items:center; gap:10px; margin-bottom:12px}
.quiz-progress{flex:1; height:8px; border-radius:2px; background:var(--chassis-dk); overflow:hidden; box-shadow:var(--seated), 0 1px 0 var(--panel-edge)}
.quiz-progress span{display:block; height:100%; width:100%; background:var(--lamp-lit); transform-origin:left center; transform:scaleX(0); transition:transform .3s cubic-bezier(.16,1,.3,1)}
.quiz-score{font-size:var(--fs-legend-lg); font-weight:700; color:var(--ink); white-space:nowrap; background:var(--card); border:1px solid var(--rule-dk); padding:3px 8px; border-radius:2px}

.q-prompt{background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r); padding:13px; margin-bottom:10px}
.q-prompt .q-kicker{margin:0 0 6px; padding-bottom:6px; border-bottom:1px solid var(--rule); font-size:var(--fs-legend-sm); text-transform:uppercase; letter-spacing:.11em; color:var(--ink-2); font-weight:700}
.q-prompt h3{margin:0; font-family:var(--font-read); font-size:var(--fs-title); line-height:1.5; font-weight:700; color:var(--ink)}

.options{display:flex; flex-direction:column; gap:6px}
.opt{
  appearance:none; cursor:pointer; text-align:left;
  font-family:var(--font-read); font-size:var(--fs-body); line-height:1.5;
  background:var(--panel); border:1px solid var(--rule-dk); color:var(--ink);
  border-radius:var(--r); padding:11px 13px; min-height:40px; box-shadow:var(--raised);
  transition:background .12s, box-shadow .12s;
}
.opt:hover:not(:disabled){background:var(--panel-hi)}
.opt:active:not(:disabled){box-shadow:var(--pressed)}
.opt:disabled{cursor:default}
.opt.correct,.opt.wrong{display:flex; align-items:flex-start; gap:9px; box-shadow:var(--pressed)}
.opt.correct::before,.opt.wrong::before{content:""; flex:0 0 auto; width:10px; height:10px; margin-top:.35em; border-radius:50%; border:1px solid var(--chassis-dk)}
.opt-mark{margin-left:auto; padding-left:10px; flex:0 0 auto; font-family:var(--font-legend); font-weight:700}
.opt.correct .opt-mark{color:#6a4a0e}
.opt.wrong .opt-mark{color:var(--amber)}
.opt.correct{background:var(--panel-hi); border-color:#8a5f14}
.opt.correct::before{background:var(--lamp-lit); box-shadow:0 0 4px var(--lamp-lit)}
.opt.wrong{background:var(--panel-lo); border-color:var(--amber)}
.opt.wrong::before{background:var(--amber-lit); box-shadow:0 0 4px var(--amber-lit)}

.feedback{margin-top:11px; padding:11px 13px; border-radius:var(--r); font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.6; background:var(--card); border:1px solid var(--rule-dk); color:var(--ink-2); display:none}
.feedback.show{display:block}
.feedback b{color:var(--ink); font-weight:700}
.feedback.good{border-color:#8a5f14}
.feedback.bad{border-color:var(--amber)}
.fb-actions{margin-top:10px}

.order-list{list-style:none; margin:0 0 11px; padding:0; display:flex; flex-direction:column; gap:4px}
.order-list li{background:var(--panel); border:1px solid var(--rule-dk); border-radius:var(--r); padding:8px 11px; font-family:var(--font-read); font-size:var(--fs-body-sm); display:flex; gap:9px; align-items:center; box-shadow:var(--flush)}
.order-list li .ord{flex:0 0 20px; height:20px; border-radius:50%; background:var(--panel-lo); border:1px solid var(--rule-dk); display:grid; place-items:center; font-size:var(--fs-legend-sm); font-weight:700; color:var(--ink)}
.order-list li.is-right{border-color:#8a5f14}
.order-list li.is-wrong{border-color:var(--amber)}
.ord-mark{margin-left:auto; font-weight:700; font-family:var(--font-legend)}
.order-list li.is-right .ord-mark{color:#7a5210}
.order-list li.is-wrong .ord-mark{color:var(--amber)}

.result-card{text-align:center; padding:20px 14px; background:var(--card); border:1px solid var(--rule-dk); border-radius:var(--r)}
.result-card .big{font-size:var(--fs-data-xl); font-weight:600; line-height:1; margin:0 0 6px; color:var(--ink)}
.result-card .big-total{font-size:var(--fs-title-lg); color:var(--ink-2)}
.result-card .grade{margin:0 0 9px; font-family:var(--font-legend); font-size:var(--fs-body-lg); font-weight:700; text-transform:uppercase; letter-spacing:.09em; color:var(--ink)}
.result-card p{font-family:var(--font-read); color:var(--ink-2); font-size:var(--fs-body); line-height:1.62}
.result-actions{margin-top:16px; justify-content:center}

/* The score screen is the last thing a student sees before closing the laptop.
   Without these the review list fell back to browser-default discs in a 40px
   indent against centred text — the only broken element in the whole panel,
   at the moment that weighs most. */
.review-list{text-align:left; margin:14px 0 0; padding:0; list-style:none}
.review-list li{
  font-family:var(--font-read); font-size:var(--fs-body-sm); color:var(--ink-2);
  padding:7px 0; border-top:1px solid var(--rule); line-height:1.5;
}
.review-list .review-head{
  border-top:0; font-family:var(--font-legend); color:var(--ink-2); font-weight:700;
  font-size:var(--fs-legend-sm); text-transform:uppercase; letter-spacing:.11em;
}

/* =========================================================
   MODAL + TOAST
   ========================================================= */
.modal{position:fixed; inset:0; z-index:60; display:grid; place-items:center; background:rgba(6,14,26,.74); padding:20px}
.modal.hidden{display:none}
.modal-card{
  color:var(--ink); position:relative; max-width:580px; width:100%; max-height:86vh; overflow-y:auto;
  background:var(--card); border:1px solid var(--chassis); border-radius:var(--r); padding:24px;
  box-shadow:0 10px 34px rgba(0,0,0,.4);
}
.modal-card h2{margin:0 0 14px; font-family:var(--font-legend); font-size:var(--fs-title); font-weight:700; text-transform:uppercase; letter-spacing:.08em; color:var(--ink)}
.modal-close{
  position:absolute; top:10px; right:12px; appearance:none; cursor:pointer;
  width:32px; height:32px; display:grid; place-items:center;
  background:var(--panel); border:1px solid var(--rule-dk); border-radius:var(--r); color:var(--ink); font-size:var(--fs-title-lg); line-height:1;
}
.modal-close:hover{background:var(--panel-hi)}
.help-list{margin:0 0 14px; padding-left:18px}
.help-list li{font-family:var(--font-read); font-size:var(--fs-body); line-height:1.65; color:var(--ink-2); margin-bottom:8px}
.help-list b{color:var(--ink); font-weight:700}
.help-route{margin:0 0 14px; padding:11px 0 0; border-top:1px solid var(--rule); font-family:var(--font-read); font-size:var(--fs-body-sm); line-height:1.65; color:var(--ink-2)}
.help-route b{color:var(--ink); font-weight:700}
.help-foot{margin:0; font-family:var(--font-read); font-size:var(--fs-body-sm); color:var(--ink-2); line-height:1.6}

.toast{
  position:fixed; bottom:24px; left:50%;
  background:var(--chassis-dk); border:1px solid #060d18; color:var(--fascia-ink);
  padding:11px 17px; border-radius:var(--r);
  font-family:var(--font-legend); font-size:var(--fs-legend-lg); font-weight:700; text-transform:uppercase; letter-spacing:.06em;
  box-shadow:0 6px 20px rgba(0,0,0,.42); z-index:70;
  transform:translate(-50%,0); opacity:1;
  transition:opacity .2s ease, transform .2s cubic-bezier(.16,1,.3,1);
}
.toast.leaving{opacity:0; transform:translate(-50%,8px)}
.toast.hidden{display:none}
.toast.good{border-color:#8a5f14; color:var(--lamp-lit)}
.toast.bad{border-color:var(--amber); color:var(--amber-lit)}

.hidden{display:none}

/* =========================================================
   POWER-UP
   ========================================================= */
@keyframes lampcheck{
  0%,100%{background:var(--lamp-off); box-shadow:var(--seated)}
  40%,60%{background:var(--lamp-lit); box-shadow:0 0 5px var(--lamp-lit)}
}
@keyframes screencome{from{opacity:0} to{opacity:1}}
body.powerup .tab-no{animation:lampcheck .5s ease-in-out 1}
body.powerup .tab:nth-child(1) .tab-no{animation-delay:0s}
body.powerup .tab:nth-child(2) .tab-no{animation-delay:.06s}
body.powerup .tab:nth-child(3) .tab-no{animation-delay:.12s}
body.powerup .tab:nth-child(4) .tab-no{animation-delay:.18s}
body.powerup .svg-wrap > svg{animation:screencome .45s ease-out .18s both}

/* =========================================================
   RESPONSIVE
   ========================================================= */
@media (max-width:1180px){.layout{grid-template-columns:minmax(0,1fr) 340px}}
@media (max-width:1000px){
  .layout{grid-template-columns:minmax(0,1fr); padding:14px}
  .panel{position:static; max-height:none; top:auto; min-height:0}
  .tabs{order:3; flex:1 0 100%; justify-content:flex-start; gap:4px; overflow-x:auto; flex-wrap:nowrap; padding-bottom:2px; scrollbar-width:thin}
  .tabs .tab{flex:0 0 auto; padding:9px 11px 9px 9px}
  .orient-note{text-align:left; max-width:none}
  #bench-view{max-height:none}
  .stage{scroll-margin-top:12px}
  .bin-grid{grid-template-columns:1fr}
}
@media (max-width:560px){
  .topbar{padding:10px 12px; gap:9px}
  .brand-text small{display:none}
  .stage{padding:11px 10px}
  .viewswitch{width:100%}
  .vbtn{flex:1}
  .svg-wrap{border-width:6px}
}

@media (prefers-reduced-motion: reduce){
  html{scroll-behavior:auto}
  *{animation-duration:.01ms !important; animation-iteration-count:1 !important; transition-duration:.01ms !important; scroll-behavior:auto !important}
  .brand-mark.lit{animation:none !important; background:var(--lamp-lit);
    box-shadow:inset 0 1px 1px rgba(255,255,255,.4), 0 0 4px var(--lamp-lit)}
}