/* ProfStack · narrated lecture system
   Layout: sticky control bar, scene list on the left, one scene at a time on a text|diagram split
   whose proportions the Layout switch changes (Text / Even / Diagram). */
:root{
  --bg:#F3F5F8; --surface:#FFFFFF; --sunk:#E9EDF2; --ink:#16202B; --muted:#5A6675; --line:#D6DDE5;
  --mark:rgba(255,205,40,.38); --good:#1E7F4F; --bad:#B4362F; --warn:#A86200;
  --wk:#2F5BD3; --wk-soft:rgba(47,91,211,.10); --on-wk:#FFFFFF;
  --f-display:"Schibsted Grotesk","Helvetica Neue",Arial,sans-serif;
  --f-body:"Source Serif 4",Georgia,"Times New Roman",serif;
  --f-mono:"JetBrains Mono",ui-monospace,Menlo,Consolas,monospace;
  --r:10px;
}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){
  --bg:#0E1318; --surface:#161D25; --sunk:#1D2630; --ink:#E5EAF0; --muted:#97A3B1; --line:#2B3642;
  --mark:rgba(255,205,40,.20); --good:#5BCB8E; --bad:#F0837A; --warn:#F0B048;
  --wk:var(--wk-d,#7C9BFF); --wk-soft:var(--wk-soft-d,rgba(124,155,255,.14)); --on-wk:#0E1318; color-scheme:dark}}
:root[data-theme="dark"]{
  --bg:#0E1318; --surface:#161D25; --sunk:#1D2630; --ink:#E5EAF0; --muted:#97A3B1; --line:#2B3642;
  --mark:rgba(255,205,40,.20); --good:#5BCB8E; --bad:#F0837A; --warn:#F0B048;
  --wk:var(--wk-d,#7C9BFF); --wk-soft:var(--wk-soft-d,rgba(124,155,255,.14)); --on-wk:#0E1318; color-scheme:dark}

*{box-sizing:border-box}
html,body{background:var(--bg);color:var(--ink)}
body{margin:0;font:17px/1.6 var(--f-body);-webkit-font-smoothing:antialiased}
a{color:var(--wk)}
button{font:inherit;color:inherit}
:focus-visible{outline:2px solid var(--wk);outline-offset:2px}
h1,h2,h3,h4{font-family:var(--f-display);line-height:1.15;text-wrap:balance;margin:0}
.mono{font-family:var(--f-mono);font-size:.78rem;letter-spacing:.04em}
.eyebrow{font-family:var(--f-mono);font-size:.72rem;letter-spacing:.09em;text-transform:uppercase;color:var(--muted)}

/* ---------- top bar ---------- */
.bar{position:sticky;top:env(safe-area-inset-top,0px);z-index:20;background:color-mix(in srgb,var(--bg) 88%,transparent);
  backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.bar-in{display:flex;flex-wrap:wrap;align-items:center;gap:10px 18px;padding:10px 20px;max-width:1440px;margin:0 auto}
.brand{display:flex;align-items:baseline;gap:10px;min-width:0;flex:1 1 260px;text-decoration:none;color:var(--ink)}
.brand b{font-family:var(--f-display);font-weight:800;font-size:1.02rem;white-space:nowrap}
.brand span{font-family:var(--f-display);color:var(--muted);font-size:.92rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.controls{display:flex;flex-wrap:wrap;align-items:center;gap:8px}
.seg{display:inline-flex;border:1px solid var(--line);border-radius:999px;padding:2px;background:var(--surface)}
.seg button{border:0;background:none;padding:5px 12px;border-radius:999px;cursor:pointer;font-family:var(--f-display);font-size:.84rem;color:var(--muted)}
.seg button[aria-pressed="true"]{background:var(--ink);color:var(--bg)}
.seg-label{font-family:var(--f-mono);font-size:.68rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin-right:2px}
.pill{border:1px solid var(--line);background:var(--surface);border-radius:999px;padding:5px 13px;cursor:pointer;font-family:var(--f-display);font-size:.84rem;display:inline-flex;align-items:center;gap:6px}
.pill[aria-pressed="true"]{border-color:var(--wk);color:var(--wk);background:var(--wk-soft)}
.pill.listen{background:var(--wk);border-color:var(--wk);color:var(--on-wk);font-weight:600}
.pill.listen[aria-pressed="true"]{background:var(--ink);border-color:var(--ink);color:var(--bg)}

/* ---------- shell ---------- */
.shell{display:grid;grid-template-columns:260px minmax(0,1fr);gap:28px;max-width:1440px;margin:0 auto;padding:22px 20px 40px}
.toc{position:sticky;top:calc(env(safe-area-inset-top,0px) + 74px);align-self:start;max-height:calc(100vh - 100px);overflow:auto}
.toc h1{font-size:1.35rem;margin:4px 0 6px}
.toc .meta{font-size:.86rem;color:var(--muted);margin-bottom:14px;font-family:var(--f-display)}
.toc ol{list-style:none;margin:0;padding:0;display:grid;gap:2px;counter-reset:s}
.toc li button{width:100%;text-align:left;border:0;background:none;padding:7px 10px;border-radius:8px;cursor:pointer;display:grid;grid-template-columns:26px 1fr;gap:6px;align-items:baseline;font-family:var(--f-display);font-size:.9rem;color:var(--muted)}
.toc li button .n{font-family:var(--f-mono);font-size:.72rem}
.toc li button:hover{background:var(--sunk);color:var(--ink)}
.toc li button[aria-current="true"]{background:var(--wk-soft);color:var(--ink);font-weight:600}
.toc li button[aria-current="true"] .n{color:var(--wk)}
.toc .kind{display:inline-block;font-family:var(--f-mono);font-size:.62rem;letter-spacing:.08em;text-transform:uppercase;border:1px solid currentColor;border-radius:4px;padding:0 4px;margin-left:6px;vertical-align:1px;opacity:.75}
.toc li.seen .n::after{content:" ✓";color:var(--good)}

/* ---------- stage ---------- */
.stage{min-width:0}
.scene-head{display:flex;flex-wrap:wrap;justify-content:space-between;align-items:end;gap:8px 20px;margin-bottom:16px}
.scene-head h2{font-size:clamp(1.6rem,3.2vw,2.5rem);font-weight:800;letter-spacing:-.015em;max-width:24ch}
.chips{display:flex;flex-wrap:wrap;gap:6px}
.chip{font-family:var(--f-mono);font-size:.7rem;letter-spacing:.06em;text-transform:uppercase;border:1px solid var(--line);border-radius:999px;padding:3px 9px;color:var(--muted);background:var(--surface)}
.chip.k-activity{border-color:var(--wk);color:var(--wk)}
.chip.k-check{border-color:var(--good);color:var(--good)}
.chip.k-exam{border-color:var(--exam);color:var(--exam)}

.split{display:grid;gap:26px;grid-template-columns:minmax(0,1fr) minmax(0,1fr);align-items:start}
body[data-layout="text"] .split{grid-template-columns:minmax(0,1fr)}
body[data-layout="text"] .split .fig{display:none}
body[data-layout="text"] .narr{max-width:68ch}
body[data-layout="diagram"] .split{grid-template-columns:minmax(0,1fr)}
body[data-layout="diagram"] .narr{order:2}
body[data-layout="diagram"] .narr .para:not(:first-child),body[data-layout="diagram"] .narr .think{display:none}
body[data-layout="diagram"] .narr .para:first-child{font-size:.95rem;color:var(--muted);max-width:80ch}
.split.nofig{grid-template-columns:minmax(0,1fr)}
.split.nofig .narr{max-width:72ch}
.split.wide{grid-template-columns:minmax(0,.85fr) minmax(0,1.15fr)}
body[data-layout="text"] .split.wide,body[data-layout="diagram"] .split.wide{grid-template-columns:minmax(0,1fr)}

.narr .para{margin:0 0 1em;padding:2px 6px;margin-left:-6px;border-radius:4px;transition:background .25s}
.narr .para.speaking{background:var(--mark)}
.narr strong{font-weight:650}
.narr .lead{font-size:1.14rem}
.narr ul{margin:0 0 1em;padding-left:1.2em}
.narr li{margin:.25em 0}
.think{border-left:3px solid var(--wk);background:var(--wk-soft);padding:12px 16px;border-radius:0 var(--r) var(--r) 0;margin:1.2em 0}
.think .eyebrow{color:var(--wk);display:block;margin-bottom:4px}
.src{font-size:.82rem;color:var(--muted);font-family:var(--f-display);border-top:1px dashed var(--line);padding-top:10px;margin-top:16px}
.notes{margin-top:20px;border:1px dashed var(--warn);border-radius:var(--r);padding:12px 16px;font-family:var(--f-display);font-size:.9rem;background:color-mix(in srgb,var(--warn) 7%,transparent)}
.notes .eyebrow{color:var(--warn);display:block;margin-bottom:4px}
.notes ul{margin:.3em 0 0;padding-left:1.1em}
body:not(.teacher) .notes{display:none}

.fig{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:18px;min-width:0}
.fig > .eyebrow{display:block;margin-bottom:10px}
.fig svg{width:100%;height:auto;display:block}
.fig svg text{font-family:var(--f-display);fill:var(--ink)}
.fig svg .t-muted{fill:var(--muted)}
.fig svg .t-mono{font-family:var(--f-mono)}
.fig .caption{font-size:.84rem;color:var(--muted);font-family:var(--f-display);margin-top:10px}

/* pager */
.pager{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:30px;padding-top:16px;border-top:1px solid var(--line)}
.pager button{border:1px solid var(--line);background:var(--surface);border-radius:var(--r);padding:10px 16px;cursor:pointer;font-family:var(--f-display);text-align:left;min-width:0;max-width:48%}
.pager button small{display:block;color:var(--muted);font-family:var(--f-mono);font-size:.68rem;letter-spacing:.08em;text-transform:uppercase}
.pager button:disabled{opacity:.35;cursor:default}
.pager .next{text-align:right;margin-left:auto;border-color:var(--wk)}
.progress{height:3px;background:var(--line);position:relative}
.progress i{position:absolute;inset:0 auto 0 0;background:var(--wk);transition:width .3s}
.kbd{font-family:var(--f-mono);font-size:.72rem;color:var(--muted)}

/* ---------- shared widgets ---------- */
.btn{border:1px solid var(--wk);background:var(--wk);color:var(--on-wk);border-radius:8px;padding:7px 14px;cursor:pointer;font-family:var(--f-display);font-weight:600;font-size:.88rem}
.btn.ghost{background:none;color:var(--wk)}
.btn:disabled{opacity:.4;cursor:default}
.row{display:flex;flex-wrap:wrap;gap:8px;align-items:center}
.stack{display:grid;gap:10px}
.ui{font-family:var(--f-display);font-size:.92rem}
.ui label{font-weight:600}
input[type=range]{width:100%;accent-color:var(--wk)}
textarea,input[type=text]{width:100%;border:1px solid var(--line);background:var(--bg);color:var(--ink);border-radius:8px;padding:8px 10px;font:inherit;font-size:.92rem;resize:vertical}
.tag{display:inline-block;font-family:var(--f-mono);font-size:.68rem;letter-spacing:.06em;text-transform:uppercase;padding:2px 7px;border-radius:4px;background:var(--sunk);color:var(--muted)}
.tag.good{background:color-mix(in srgb,var(--good) 15%,transparent);color:var(--good)}
.tag.bad{background:color-mix(in srgb,var(--bad) 15%,transparent);color:var(--bad)}
.tag.warn{background:color-mix(in srgb,var(--warn) 15%,transparent);color:var(--warn)}
.feedback{font-family:var(--f-display);font-size:.88rem;padding:8px 12px;border-radius:8px;background:var(--sunk)}

/* quiz */
.quiz{display:grid;gap:18px}
.q{border:1px solid var(--line);border-radius:var(--r);padding:14px 16px;background:var(--bg)}
.q h4{font-size:1rem;margin-bottom:10px;font-weight:650}
.q .opts{display:grid;gap:6px}
.q .opt{border:1px solid var(--line);background:var(--surface);border-radius:8px;padding:8px 12px;text-align:left;cursor:pointer;font-family:var(--f-display);font-size:.92rem}
.q .opt:hover:not(:disabled){border-color:var(--wk)}
.q .opt.right{border-color:var(--good);background:color-mix(in srgb,var(--good) 12%,transparent)}
.q .opt.wrong{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 10%,transparent)}
.q .opt:disabled{cursor:default}
.q .why{margin-top:8px}
.score{font-family:var(--f-display);font-weight:700}

/* sort */
.sort{display:grid;gap:8px}
.sort .item{display:grid;grid-template-columns:minmax(0,1fr) auto;gap:8px 12px;align-items:center;border:1px solid var(--line);border-radius:8px;padding:8px 10px;background:var(--bg)}
.sort .item p{margin:0;font-family:var(--f-display);font-size:.92rem}
.sort .choices{display:flex;flex-wrap:wrap;gap:4px}
.sort .choices button{border:1px solid var(--line);background:var(--surface);border-radius:6px;padding:3px 8px;font-family:var(--f-display);font-size:.78rem;cursor:pointer}
.sort .choices button[aria-pressed="true"]{background:var(--ink);color:var(--bg);border-color:var(--ink)}
.sort .item .why{grid-column:1/-1;font-family:var(--f-display);font-size:.84rem;color:var(--muted)}

/* worksheet */
.ws{display:grid;gap:12px}
.ws .f label{display:block;font-family:var(--f-display);font-weight:600;font-size:.9rem;margin-bottom:4px}
.ws .f small{display:block;color:var(--muted);font-family:var(--f-display);font-size:.8rem;margin-bottom:4px}

/* poll */
.poll{display:grid;gap:8px}
.poll button.o{display:grid;grid-template-columns:minmax(0,1fr) auto;align-items:center;gap:8px;border:1px solid var(--line);background:var(--bg);border-radius:8px;padding:9px 12px;text-align:left;cursor:pointer;font-family:var(--f-display);font-size:.92rem}
.poll button.o[aria-pressed="true"]{border-color:var(--wk);background:var(--wk-soft)}

/* ---------- four-step boxes (from the lecture decks) ---------- */
:root{--plain:#6B4FB8;--ex:#2563A8;--exam:#9A5B00}
@media (prefers-color-scheme: dark){:root:not([data-theme="light"]){--plain:#B9A3F5;--ex:#7DB3F0;--exam:#F0B048}}
:root[data-theme="dark"]{--plain:#B9A3F5;--ex:#7DB3F0;--exam:#F0B048}
.box{border-radius:10px;padding:10px 14px;border:1px solid;font-size:.97rem}
.box > b.lbl{display:block;font-family:var(--f-mono);font-size:.68rem;letter-spacing:.1em;text-transform:uppercase;font-weight:600;margin-bottom:3px}
.box.plain{border-color:color-mix(in srgb,var(--plain) 45%,transparent);background:color-mix(in srgb,var(--plain) 8%,transparent)}
.box.plain > b.lbl{color:var(--plain)}
.box.ex{border-color:color-mix(in srgb,var(--ex) 45%,transparent);background:color-mix(in srgb,var(--ex) 8%,transparent)}
.box.ex > b.lbl{color:var(--ex)}
.box.exam{border-color:color-mix(in srgb,var(--exam) 55%,transparent);background:color-mix(in srgb,var(--exam) 10%,transparent)}
.box.exam > b.lbl{color:var(--exam)}
.box ul{margin:.3em 0 0;padding-left:1.1em}
.para:has(> .box){padding:0;margin-left:0}
.para.speaking > .box{outline:3px solid var(--mark)}
.legend{display:flex;flex-wrap:wrap;gap:6px 14px;font-family:var(--f-display);font-size:.82rem;color:var(--muted)}
.legend i{display:inline-block;width:10px;height:10px;border-radius:2px;margin-right:5px;vertical-align:-1px}

/* tables used inside narration/figures */
.tbl{width:100%;border-collapse:collapse;font-family:var(--f-display);font-size:.86rem}
.tbl th,.tbl td{border-bottom:1px solid var(--line);padding:7px 8px;text-align:left;vertical-align:top}
.tbl th{font-family:var(--f-mono);font-size:.66rem;letter-spacing:.07em;text-transform:uppercase;color:var(--muted);font-weight:400}
.tbl td:first-child{font-weight:650}

/* picker (tiles that reveal detail) */
.picker{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px}
.picker h4{font-family:var(--f-mono);font-size:.68rem;letter-spacing:.08em;text-transform:uppercase;color:var(--muted);margin-bottom:6px}
.picker button{display:block;width:100%;text-align:left;border:1px solid var(--line);background:var(--bg);border-radius:8px;padding:7px 10px;margin-bottom:6px;cursor:pointer;font-family:var(--f-display);font-size:.87rem}
.picker button[aria-pressed="true"]{border-color:var(--wk);background:var(--wk-soft)}
.pick-detail{margin-top:10px;font-family:var(--f-display);font-size:.92rem;border-top:1px solid var(--line);padding-top:10px}
.pick-detail p{margin:.4em 0 0}

/* accordion */
.acc{display:grid;gap:8px}
.acc details{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:9px 12px;font-family:var(--f-display);font-size:.92rem}
.acc summary{cursor:pointer;font-weight:650}
.acc p{margin:.45em 0 0}

/* practice questions */
.prac{display:grid;gap:8px}
.prac .pq{border:1px solid var(--line);border-radius:8px;background:var(--bg);padding:10px 12px;font-family:var(--f-display);font-size:.92rem}
.prac .pq .row{justify-content:space-between}
.prac .pq .hint{margin-top:8px;border-left:3px solid var(--exam);padding-left:10px;color:var(--ink)}

/* flashcards */
.fc-tools{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-bottom:10px;font-family:var(--f-display);font-size:.88rem}
.fc{display:grid;grid-template-columns:repeat(auto-fill,minmax(190px,1fr));gap:8px}
.fc button{border:1px solid var(--line);background:var(--bg);border-radius:10px;padding:12px;text-align:left;cursor:pointer;min-height:92px;display:flex;flex-direction:column;gap:6px;font-family:var(--f-display)}
.fc button b{font-size:.98rem}
.fc button span{font-size:.85rem;color:var(--muted)}
.fc.test button:not(.open) span{visibility:hidden}
.fc.test button:not(.open)::after{content:"Tap to reveal";font-family:var(--f-mono);font-size:.66rem;color:var(--muted);letter-spacing:.06em;text-transform:uppercase;margin-top:auto}
.fc button.known{border-color:var(--good)}

/* order game */
.order{display:flex;flex-wrap:wrap;gap:8px}
.order button{border:1px solid var(--line);background:var(--bg);border-radius:8px;padding:8px 10px;cursor:pointer;font-family:var(--f-display);font-size:.86rem;text-align:left;max-width:240px}
.order button.done{border-color:var(--good);background:color-mix(in srgb,var(--good) 12%,transparent);cursor:default}
.order button.no{animation:shake .3s}
.order button .yr{font-family:var(--f-mono);font-weight:600;color:var(--good)}
@keyframes shake{25%{transform:translateX(-4px)}75%{transform:translateX(4px)}}

/* full-width figure under the narration */
.split.full{grid-template-columns:minmax(0,1fr)}
.split.full .narr{max-width:76ch}

/* video */
.videos{display:grid;gap:12px;margin:1.2em 0}
.video{border:1px solid var(--line);border-radius:12px;overflow:hidden;background:var(--surface)}
.vframe{position:relative;aspect-ratio:16/9;max-width:100%;background:#000}
.vframe iframe{position:absolute;inset:0;width:100%;height:100%;border:0}
.vcard{display:flex;gap:14px;align-items:center;padding:14px 16px;text-decoration:none;color:var(--ink);background:var(--wk-soft);font-family:var(--f-display)}
.vcard b{display:block}.vcard small{color:var(--muted)}
.vplay{width:46px;height:46px;border-radius:50%;background:var(--wk);color:var(--on-wk);display:grid;place-items:center;font-size:1.1rem;flex:none}
.vmeta{padding:10px 14px;font-family:var(--f-display);font-size:.9rem}
.vmeta b{display:block;margin:2px 0}
.vmeta p{margin:.3em 0;color:var(--muted)}

/* flowchart */
.fsteps{display:flex;flex-wrap:wrap;align-items:stretch;gap:6px}
.fstep{flex:1 1 110px;border:1.5px solid var(--line);background:var(--bg);border-radius:10px;padding:9px 10px;text-align:left;cursor:pointer;font-family:var(--f-display);display:flex;flex-direction:column;gap:2px;transition:background .25s,border-color .25s,transform .25s}
.fstep .fn{font-family:var(--f-mono);font-size:.66rem;color:var(--muted)}
.fstep b{font-size:.9rem}.fstep small{font-size:.76rem;color:var(--muted)}
.fstep.done{border-color:color-mix(in srgb,var(--wk) 45%,var(--line))}
.fstep.on{border-color:var(--wk);background:var(--wk-soft);transform:translateY(-2px)}
.farrow{align-self:center;color:var(--muted);font-family:var(--f-mono)}

/* mind map */
.mmap svg{width:100%;max-width:720px;height:auto;display:block;overflow:visible;margin:0 auto}
.mm-b{cursor:pointer}
.mm-b:focus-visible rect{stroke:var(--ink)}
.mm-c{height:100%;display:flex;align-items:center;justify-content:center;text-align:center;color:var(--on-wk);font:700 13px/1.2 var(--f-display)}
.mm-t{height:100%;display:flex;align-items:center;justify-content:center;text-align:center;color:var(--ink);font:600 12.5px/1.15 var(--f-display)}
.mm-l{height:100%;display:flex;align-items:center;color:var(--ink);font:12px/1.25 var(--f-display)}
.mm-center{display:inline-block;background:var(--wk);color:var(--on-wk);border-radius:999px;padding:8px 16px;font-family:var(--f-display);font-weight:700;margin-bottom:10px}
.mmap .acc ul{margin:.4em 0 0;padding-left:1.1em}

/* ---------- responsive ---------- */
@media (max-width:900px){
  .shell{grid-template-columns:minmax(0,1fr);padding:16px 16px 40px}
  .toc{position:static;max-height:none}
  .toc ol{display:flex;overflow-x:auto;gap:4px;padding-bottom:6px}
  .toc li button{white-space:nowrap;grid-template-columns:auto auto}
  .toc li button .t{display:none}
  .toc li button[aria-current="true"] .t{display:inline}
  .split,.split.wide{grid-template-columns:minmax(0,1fr)}
  .bar-in{padding:8px 16px}
  .brand span{display:none}
}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}

.support-note{max-width:1440px;margin:0 auto;padding:14px 20px 90px;border-top:1px solid var(--line);font-family:var(--f-display);font-size:.84rem;color:var(--muted);text-align:center}

/* learning supports: practice methods */
.prac .qb{display:flex;gap:6px;flex:none}
.prac .spk{padding:4px 9px}
.calm-start{border:1px solid var(--line);border-radius:10px;background:var(--surface);padding:10px 12px;font-family:var(--f-display);font-size:.92rem}
.calm-start summary{cursor:pointer;font-weight:700}
.calm-start textarea{width:100%;min-height:70px;border:1px solid var(--line);border-radius:8px;padding:8px;font:inherit;background:var(--bg);color:var(--ink)}
.calm-start .re{color:var(--muted)}
.prac .pnav{display:flex;align-items:center;justify-content:space-between;gap:8px;font-family:var(--f-display)}
.prac .pnav .pc{font-weight:700}
.prac .selfmon{display:grid;gap:4px;margin-top:10px;padding-top:8px;border-top:1px dashed var(--line);font-size:.86rem;color:var(--muted)}
.prac .selfmon label{display:flex;gap:8px;align-items:center;color:var(--ink)}
.guide{margin-top:8px}
.gsteps{margin:0;padding-left:22px;display:grid;gap:6px}
.gsteps li.todo{color:var(--muted)}
.gsteps li.done{color:var(--muted)}
.gsteps>li.done>b::after{content:" ✓";color:var(--good)}
.gsteps>li>b{color:inherit}
.gsteps>li.cur>b{color:var(--wk)}
.gsteps>li{display:list-item}
.wsteps .ws{display:block}
.wsteps .ws b{display:inline;color:var(--ink);font-size:inherit}
.wsteps{display:grid;gap:6px;margin-top:6px}
.wsteps .ws{border-left:3px solid var(--wk);padding:4px 10px;background:var(--wk-soft);border-radius:4px}
.wsteps .ws > div{display:grid;grid-template-columns:auto minmax(0,1fr);gap:8px}
.wsteps .ws span:first-child{font-weight:700}
.gbtn{margin-top:8px;display:flex;gap:6px;align-items:center;flex-wrap:wrap}
.gok{color:var(--good);font-weight:700}

/* ---------- practice: solve → save → enter result → model answer ---------- */
.prac .gate{margin-top:10px;border:1px dashed var(--line);border-radius:10px;padding:10px 12px;display:grid;gap:8px;background:var(--surface)}
.prac .gs{display:grid;grid-template-columns:26px minmax(0,1fr);gap:4px 8px;align-items:start;border:0;margin:0;padding:0;min-width:0}
.prac .gs>b{display:inline-grid;place-items:center;width:24px;height:24px;border-radius:50%;background:var(--wk);color:var(--on-wk,#fff);font-size:.8rem}
.prac .gs.done>b{background:var(--good)}
.prac .gs.done>b::after{content:"";}
.prac .gs .paper{grid-column:2;display:flex;gap:8px;align-items:center;font-size:.86rem;color:var(--muted)}
.prac fieldset.gs[disabled]{opacity:.45}
.prac .gfs{grid-column:2;display:flex;flex-wrap:wrap;gap:8px 14px}
.prac .gf{display:flex;align-items:center;gap:6px;font-size:.88rem}
.prac .gf>span{color:var(--muted)}
.prac .gf input,.prac .gf select{font:600 1rem var(--f-mono);width:8.5em;padding:6px 8px;border:1.5px solid var(--line);border-radius:8px;background:var(--bg);color:var(--ink)}
.prac .gf select{width:auto;font-family:var(--f-display)}
.prac .gf em{font-style:normal;color:var(--muted)}
.prac .gf.ok input,.prac .gf.ok select{border-color:var(--good);background:color-mix(in srgb,var(--good) 10%,var(--bg))}
.prac .gf.bad input,.prac .gf.bad select{border-color:var(--bad);background:color-mix(in srgb,var(--bad) 8%,var(--bg))}
.prac .gf.ok .gm::after{content:"✓";color:var(--good);font-weight:700;font-style:normal}
.prac .gf.bad .gm::after{content:"✗";color:var(--bad);font-weight:700;font-style:normal}
.prac .gchk{grid-column:2;justify-self:start}
.prac .gmsg{margin:0;font-size:.9rem;min-height:1em}
.prac .gate.open{border-style:solid;border-color:var(--good)}
.prac .gate.open .g2{display:none}
.prac .show[disabled]{opacity:.6;cursor:not-allowed}
.prac .wspace{display:grid;grid-template-columns:minmax(0,1fr) 300px;gap:12px;align-items:start}
.prac .wpad{min-width:0}
.prac .wcalc{position:sticky;top:80px}
.prac .wsave{margin-top:8px}
.prac .wsaved{font-size:.86rem;color:var(--muted)}
@media (max-width:760px){.prac .wspace{grid-template-columns:minmax(0,1fr)}.prac .wcalc{position:static;justify-self:center;width:100%;max-width:300px}}

/* ---------- every model answer in the professor's handwriting (board look, also in dark mode) ---------- */
.prac .pq .hint{border-left:0;padding-left:0;font-family:BoardHand,'Segoe Print','Bradley Hand',cursive;font-size:1.2rem;line-height:1.45;color:#1c3a9c}
.prac .pq .hint:not(:has(.mg,.bd)){background:#fbfaf5;border:1px solid #d6d2c6;border-radius:10px;padding:10px 16px;box-shadow:inset 0 0 50px rgba(0,0,0,.04)}
.prac .hint .mg{background:#fbfaf5;color:#1c3a9c;border:1px solid #d6d2c6;border-radius:10px;padding:10px 16px;margin:10px 0;box-shadow:inset 0 0 50px rgba(0,0,0,.04);gap:6px}
.prac .hint .mg>div{grid-template-columns:110px minmax(0,1fr)}
.prac .hint .mg>div>span:first-child{font-family:BoardHand,cursive;font-size:1rem;letter-spacing:0;text-transform:none;color:#c62828;padding-top:2px}
.prac .hint .mg b,.prac .hint b{font-weight:700;color:#1c3a9c}
.prac .hint .mg .fin>span:last-child b{border-bottom:3px solid #c62828;padding:0 .1em}
.prac .hint .mg .how{font-family:var(--f-mono);font-size:.7rem;color:#6b7280;font-style:normal}
.prac .hint .tbl,.prac .hint .tbl th,.prac .hint .tbl td{font-family:BoardHand,cursive;color:#1c3a9c;border-color:#1c3a9c;background:transparent}
.prac .hint .keys kbd{font-family:"JetBrains Mono",Consolas,monospace;color:#20232a}
.prac .hint svg text{font-family:BoardHand,cursive}
@media (max-width:560px){.prac .hint .mg>div{grid-template-columns:minmax(0,1fr)}}
.prac .hint .mg>div.how{grid-template-columns:minmax(0,1fr)}
.prac .hint .mg>div.how>span:first-child{font-family:var(--f-mono);font-size:.7rem;color:#6b7280;letter-spacing:.02em}
.prac .gtries{color:var(--muted);font-size:.84rem;margin-left:4px}
.prac .gate.recap{border-color:var(--warn)}
.prac .grecap{border-left:4px solid var(--warn);background:color-mix(in srgb,var(--warn) 9%,var(--surface));border-radius:0 8px 8px 0;padding:8px 12px;display:grid;gap:4px}
.prac .grecap>b{font-family:var(--f-mono);font-size:.72rem;letter-spacing:.08em;text-transform:uppercase;color:var(--warn)}
.prac .grecap a{font-weight:700;justify-self:start}
.prac .grecap p{margin:0;font-size:.86rem;color:var(--muted)}
/* two graphs or two formulas: side by side, never one under the other; on phones swipe between them */
.side2{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:14px;align-items:start}
.side2>*{min-width:0}
.side2>figure,.side2>div{margin:0}
.side2 .s2-cap{display:block;font-family:var(--f-mono);font-size:.72rem;letter-spacing:.06em;text-transform:uppercase;color:var(--muted);margin-bottom:4px}
.side2-hint{display:none;font-family:var(--f-mono);font-size:.72rem;color:var(--muted);text-align:center;margin-top:4px}
@media (max-width:640px){.side2{display:flex;overflow-x:auto;scroll-snap-type:x mandatory;gap:12px;padding-bottom:6px}.side2>*{flex:0 0 88%;scroll-snap-align:start}.side2+.side2-hint{display:block}}
.prac .gfs{min-width:0}
.prac .gf{flex-wrap:wrap;max-width:100%;min-width:0}
.prac .gf select{max-width:100%;white-space:normal}