/* MAD Study Hub - warm paper look, three subject accents, light + dark. */
:root{
  --bg:#fbf9f4; --surface:#ffffff; --surface2:#f4f0e7; --text:#1f1d1a; --muted:#6a665e; --line:#e4dfd4;
  --acc:#b45f06; --acc-ink:#ffffff; --acc-soft:#fbeedd;
  --mlf:#b45f06; --mlt:#1f7a5c; --mlp:#3556c8;
  --ok:#1f7a3d; --okbg:#e8f5ec; --bad:#b3261e; --badbg:#fdecea;
  --c-eli5:#fff6d6; --c-eli5b:#e2b93b;
  --c-concept:#f4f0e7; --c-conceptb:#9b8f77;
  --c-example:#e8f5ec; --c-exampleb:#2f9a56;
  --c-practice:#e8f0ff; --c-practiceb:#4a72d9;
  --c-trap:#fdecea; --c-trapb:#d2453a;
  --c-recap:#f1eaff; --c-recapb:#8052d6;
  --c-exam:#eef1f4; --c-examb:#5d6f80;
  --c-tip:#e6f6f6; --c-tipb:#2a9a9a;
  --c-twin:#fff0e6; --c-twinb:#d9742c;
  --c-formulas:#f4f0e7; --c-formulasb:#9b8f77;
  --c-words:#eef6ea; --c-wordsb:#6f9a45;
  --radius:14px; --shadow:0 1px 2px rgba(0,0,0,.05),0 4px 14px rgba(40,30,10,.06);
  --font:ui-sans-serif,system-ui,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
  --mono:ui-monospace,"Cascadia Code",Consolas,Menlo,monospace;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme=light]){
    --bg:#15140f; --surface:#1d1c16; --surface2:#262419; --text:#ece8de; --muted:#a39e92; --line:#35322a;
    --acc-soft:#2e2414; --mlf:#e8a85a; --mlt:#5fc3a0; --mlp:#8ea6ff;
    --ok:#6ec98a; --okbg:#173022; --bad:#f2857c; --badbg:#37201e;
    --c-eli5:#322b12; --c-eli5b:#a88a23; --c-concept:#262419; --c-conceptb:#6f664f;
    --c-example:#16301f; --c-exampleb:#3a9b5d; --c-practice:#172338; --c-practiceb:#4a72d9;
    --c-trap:#341c1a; --c-trapb:#c04c42; --c-recap:#251c38; --c-recapb:#8e66e0;
    --c-exam:#20252b; --c-examb:#6c7e8f; --c-tip:#13302f; --c-tipb:#2f9c9c;
    --c-twin:#352215; --c-twinb:#d9742c; --c-formulas:#262419; --c-formulasb:#6f664f;
    --c-words:#1d2a16; --c-wordsb:#6f9a45;
    --shadow:0 1px 2px rgba(0,0,0,.4);
  }
}
:root[data-theme=dark]{
  --bg:#15140f; --surface:#1d1c16; --surface2:#262419; --text:#ece8de; --muted:#a39e92; --line:#35322a;
  --acc-soft:#2e2414; --mlf:#e8a85a; --mlt:#5fc3a0; --mlp:#8ea6ff;
  --ok:#6ec98a; --okbg:#173022; --bad:#f2857c; --badbg:#37201e;
  --c-eli5:#322b12; --c-eli5b:#a88a23; --c-concept:#262419; --c-conceptb:#6f664f;
  --c-example:#16301f; --c-exampleb:#3a9b5d; --c-practice:#172338; --c-practiceb:#4a72d9;
  --c-trap:#341c1a; --c-trapb:#c04c42; --c-recap:#251c38; --c-recapb:#8e66e0;
  --c-exam:#20252b; --c-examb:#6c7e8f; --c-tip:#13302f; --c-tipb:#2f9c9c;
  --c-twin:#352215; --c-twinb:#d9742c; --c-formulas:#262419; --c-formulasb:#6f664f;
  --c-words:#1d2a16; --c-wordsb:#6f9a45;
  --shadow:0 1px 2px rgba(0,0,0,.4);
}
body[data-subject=mlf]{--acc:var(--mlf)} body[data-subject=mlt]{--acc:var(--mlt)} body[data-subject=mlp]{--acc:var(--mlp)}

*{box-sizing:border-box}
html{scroll-behavior:smooth;-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--text);font:17px/1.7 var(--font);}
a{color:var(--acc);text-underline-offset:3px}
a:hover{text-decoration-thickness:2px}
img{max-width:100%;height:auto}
code{font-family:var(--mono);font-size:.88em;background:var(--surface2);padding:.1em .38em;border-radius:6px}
pre{background:var(--surface2);border:1px solid var(--line);border-radius:12px;padding:14px 16px;overflow:auto;line-height:1.5}
pre code{background:none;padding:0;font-size:.86em}

/* ---------- top bar ---------- */
.top{position:sticky;top:0;z-index:50;background:color-mix(in srgb,var(--bg) 88%,transparent);backdrop-filter:blur(10px);
  border-bottom:1px solid var(--line)}
.top-in{max-width:1280px;margin:0 auto;padding:10px 20px;display:flex;align-items:center;gap:10px 14px;flex-wrap:wrap;position:relative}
.brand{font-weight:800;letter-spacing:-.01em;color:var(--text);text-decoration:none;font-size:1.05rem;white-space:nowrap}
.brand span{color:var(--acc)}
.nav{display:flex;gap:2px;flex-wrap:wrap;flex:1}
.nav a{padding:6px 11px;border-radius:999px;color:var(--text);text-decoration:none;font-size:.9rem;font-weight:600}
.nav a:hover{background:var(--surface2)}
.nav a[aria-current=page]{background:var(--acc);color:var(--acc-ink)}
.tools{display:flex;gap:8px;align-items:center}
#q{width:170px;padding:7px 12px;border-radius:999px;border:1px solid var(--line);background:var(--surface);color:var(--text);font:inherit;font-size:.9rem}
#q:focus{outline:2px solid var(--acc);outline-offset:1px}
.iconbtn{border:1px solid var(--line);background:var(--surface);color:var(--text);border-radius:999px;padding:6px 11px;font:inherit;font-size:.85rem;cursor:pointer}
#results{position:absolute;right:20px;top:100%;z-index:60;width:min(420px,calc(100vw - 24px));max-height:min(70vh,560px);overflow-y:auto;overscroll-behavior:contain;background:var(--surface);
  border:1px solid var(--line);border-radius:12px;box-shadow:var(--shadow);display:none;padding:6px}
#results a{display:block;padding:8px 10px;border-radius:8px;text-decoration:none;color:var(--text)}
#results a:hover{background:var(--surface2)}
#results small{color:var(--muted);display:block}

/* ---------- layout ---------- */
.wrap{max-width:1280px;margin:0 auto;padding:22px 20px 70px}
.lesson-layout{display:grid;grid-template-columns:250px minmax(0,1fr) 210px;gap:32px;align-items:start}
.side,.toc{position:sticky;top:76px;max-height:calc(100vh - 92px);overflow:auto;font-size:.9rem}
.side h4,.toc h4{margin:0 0 8px;font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted)}
.side a,.toc a{display:flex;gap:8px;align-items:baseline;padding:6px 10px;border-radius:9px;color:var(--text);text-decoration:none;line-height:1.35}
.side a:hover,.toc a:hover{background:var(--surface2)}
.side a[aria-current=page]{background:var(--acc-soft);color:var(--acc);font-weight:700}
.side .wn{font-variant-numeric:tabular-nums;color:var(--muted);min-width:1.6em;font-weight:700}
.side .done::after{content:"\2713";margin-left:auto;color:var(--ok);font-weight:800}
.toc a{padding:4px 10px;color:var(--muted);border-left:2px solid var(--line);border-radius:0}
.toc a.on{color:var(--acc);border-left-color:var(--acc);font-weight:700}
.weeks-btn{display:none}
article{min-width:0}
.crumb{font-size:.85rem;color:var(--muted);margin:0 0 6px}
.crumb a{color:var(--muted)}
article h1{font-size:2.05rem;line-height:1.2;margin:0 0 6px;letter-spacing:-.02em}
.subtitle{color:var(--muted);margin:0 0 14px;font-size:1.05rem}
article h2{font-size:1.45rem;line-height:1.25;margin:2.3em 0 .5em;padding-top:.3em;letter-spacing:-.01em;scroll-margin-top:80px}
article h3{font-size:1.15rem;margin:1.7em 0 .3em;scroll-margin-top:80px}
article p{margin:.8em 0}
article li{margin:.3em 0}
.meta-row{display:flex;flex-wrap:wrap;gap:8px;margin:10px 0 18px}
.chip{display:inline-flex;gap:6px;align-items:center;background:var(--surface);border:1px solid var(--line);border-radius:999px;padding:3px 12px;font-size:.82rem;color:var(--muted)}
.chip b{color:var(--text)}
.official{font-size:.88rem;color:var(--muted);border-left:3px solid var(--acc);padding:4px 12px;margin:8px 0 14px;background:var(--surface);border-radius:0 10px 10px 0}
.needs{background:var(--surface);border:1px dashed var(--line);border-radius:12px;padding:10px 14px;font-size:.93rem;margin:10px 0}

/* ---------- callouts ---------- */
.callout{border-radius:var(--radius);padding:14px 18px 8px;margin:1.3em 0;border:1px solid var(--line);border-left:5px solid var(--cb,#999);background:var(--cbg,var(--surface))}
.callout>.clabel,.quiz>.clabel,.widget-box>.wlabel{font-size:.74rem;text-transform:uppercase;letter-spacing:.09em;font-weight:800;color:var(--cb,var(--muted));margin:0 0 4px}
.callout.eli5{--cbg:var(--c-eli5);--cb:var(--c-eli5b)}
.callout.concept{--cbg:var(--c-concept);--cb:var(--c-conceptb)}
.callout.example{--cbg:var(--c-example);--cb:var(--c-exampleb)}
.callout.practice{--cbg:var(--c-practice);--cb:var(--c-practiceb)}
.callout.trap{--cbg:var(--c-trap);--cb:var(--c-trapb)}
.callout.recap{--cbg:var(--c-recap);--cb:var(--c-recapb)}
.callout.exam{--cbg:var(--c-exam);--cb:var(--c-examb)}
.callout.tip{--cbg:var(--c-tip);--cb:var(--c-tipb)}
.callout.twin{--cbg:var(--c-twin);--cb:var(--c-twinb)}
.callout.formulas{--cbg:var(--c-formulas);--cb:var(--c-formulasb)}
.callout.words{--cbg:var(--c-words);--cb:var(--c-wordsb)}
.callout .clabel{color:var(--cb)}
.callout p:first-of-type{margin-top:.3em}
details{margin:.8em 0}
details>summary{cursor:pointer;font-weight:700;color:var(--acc);padding:6px 0;list-style:none}
details>summary::before{content:"\25B8  ";}
details[open]>summary::before{content:"\25BE  ";}
details.sol{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:2px 14px}
details.sol[open]{padding-bottom:8px}
details.hint{background:transparent}
.solbody{border-top:1px dashed var(--line);margin-top:4px}
.mathblock{overflow-x:auto;overflow-y:hidden;padding:2px 0;margin:.7em 0;text-align:center}
.katex{font-size:1.06em}
.tablewrap{overflow-x:auto;margin:1em 0}
table{border-collapse:collapse;width:100%;font-size:.93rem}
th,td{border-bottom:1px solid var(--line);padding:8px 10px;text-align:left;vertical-align:top}
th{font-size:.74rem;text-transform:uppercase;letter-spacing:.06em;color:var(--muted)}
blockquote{margin:1em 0;padding:.2em 1em;border-left:4px solid var(--line);color:var(--muted)}
figure.fig{margin:1.5em 0;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:12px}
figure.fig svg{width:100%;height:auto;display:block}
figcaption{font-size:.86rem;color:var(--muted);margin-top:8px;text-align:center}
svg .t{fill:var(--text);font:600 13px var(--font)} svg .m{fill:var(--muted);font:12px var(--font)}
svg .acc{stroke:var(--acc);fill:none} svg .accf{fill:var(--acc)} svg .ln{stroke:var(--muted);fill:none}
svg .ok{stroke:var(--ok);fill:none} svg .okf{fill:var(--ok)} svg .bd{stroke:var(--bad);fill:none} svg .bdf{fill:var(--bad)}
svg .pt{fill:var(--text)} svg .soft{fill:var(--acc-soft);stroke:none} svg .box{fill:var(--surface2);stroke:var(--line)}
.math-error{color:var(--bad);font-family:var(--mono)}

/* ---------- quiz + widgets ---------- */
.quiz,.widget-box{border:1px solid var(--line);border-radius:var(--radius);background:var(--surface);padding:14px 18px;margin:1.4em 0}
.quiz-item{padding:12px 0;border-top:1px solid var(--line)}
.quiz-item:first-of-type{border-top:0}
.qq{font-weight:600;margin:.2em 0 .5em}
.hint{font-weight:400;color:var(--muted);font-size:.85rem}
.qopts{list-style:none;margin:0;padding:0}
.qopts li{border:1px solid var(--line);border-radius:10px;padding:8px 12px;margin:6px 0;cursor:pointer;background:var(--bg)}
.qopts li:hover{border-color:var(--acc)}
.qopts li.sel{border-color:var(--acc);box-shadow:inset 0 0 0 1px var(--acc)}
.qopts li.right{background:var(--okbg);border-color:var(--ok)}
.qopts li.wrong{background:var(--badbg);border-color:var(--bad)}
.qcheck,.btn{background:var(--acc);color:var(--acc-ink);border:0;border-radius:10px;padding:8px 16px;font:inherit;font-weight:700;font-size:.9rem;cursor:pointer}
.btn.ghost{background:transparent;color:var(--acc);border:1px solid var(--acc)}
.qexp{display:none;margin-top:10px;padding:10px 14px;border-radius:10px;background:var(--surface2);font-size:.95rem}
.qexp.show{display:block}
.widget canvas,.widget svg{max-width:100%}
.widget .row{display:flex;flex-wrap:wrap;gap:14px;align-items:center;margin:8px 0}
.widget label{font-size:.88rem;color:var(--muted)}
.widget input[type=range]{accent-color:var(--acc);width:200px;max-width:100%}
.widget .out{font-family:var(--mono);font-size:.9rem;background:var(--surface2);padding:6px 10px;border-radius:8px;display:inline-block;margin:4px 6px 4px 0}
.widget svg{background:var(--bg);border:1px solid var(--line);border-radius:10px;display:block;width:100%;height:auto}

/* ---------- nav between lessons ---------- */
.pager{display:flex;justify-content:space-between;gap:12px;margin:46px 0 10px;flex-wrap:wrap}
.pager a{flex:1;min-width:200px;border:1px solid var(--line);border-radius:var(--radius);padding:12px 16px;text-decoration:none;color:var(--text);background:var(--surface)}
.pager a:hover{border-color:var(--acc)}
.pager small{display:block;color:var(--muted);font-size:.75rem;text-transform:uppercase;letter-spacing:.07em}
.pager .next{text-align:right}
.donebar{display:flex;gap:10px;align-items:center;flex-wrap:wrap;margin:26px 0}

/* ---------- home + cards ---------- */
.hero{padding:30px 0 14px}
.hero h1{font-size:2.7rem;line-height:1.1;margin:0 0 12px;letter-spacing:-.03em;max-width:18ch}
.hero p{font-size:1.15rem;color:var(--muted);max-width:60ch}
.cards{display:grid;grid-template-columns:repeat(auto-fit,minmax(min(290px,100%),1fr));gap:16px;margin:22px 0}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:18px 20px;box-shadow:var(--shadow)}
.card h3{margin:0 0 4px;font-size:1.25rem}
.card .tag{color:var(--muted);font-size:.93rem;margin:0 0 12px}
.card.mlf{border-top:4px solid var(--mlf)} .card.mlt{border-top:4px solid var(--mlt)} .card.mlp{border-top:4px solid var(--mlp)}
.wk{display:grid;grid-template-columns:repeat(6,1fr);gap:6px;margin:10px 0}
.wk a{display:block;text-align:center;padding:7px 0;border-radius:9px;border:1px solid var(--line);text-decoration:none;color:var(--text);font-weight:700;font-size:.9rem;background:var(--bg)}
.wk a:hover{border-color:var(--acc);color:var(--acc)}
.wk a.done{background:var(--okbg);border-color:var(--ok);color:var(--ok)}
.bigcta{display:flex;gap:14px;flex-wrap:wrap;margin:18px 0}
.bigcta a{display:block;flex:1;min-width:260px;background:var(--acc-soft);border:1px solid var(--line);border-left:5px solid var(--acc);border-radius:var(--radius);padding:16px 18px;text-decoration:none;color:var(--text)}
.bigcta a:hover{border-color:var(--acc)}
.bigcta b{display:block;font-size:1.05rem;color:var(--acc)}
.sec{font-size:1.4rem;margin:2.2em 0 .2em;letter-spacing:-.01em}
.lead{color:var(--muted);margin:.2em 0 1em;max-width:70ch}
.stat{display:flex;gap:26px;flex-wrap:wrap;margin:14px 0}
.stat div{min-width:100px} .stat b{font-size:1.8rem;display:block;line-height:1.1} .stat span{font-size:.82rem;color:var(--muted)}

/* ---------- papers ---------- */
.plist{width:100%}
.plist td a{font-weight:700}
.pill{display:inline-block;font-size:.72rem;font-weight:700;padding:2px 9px;border-radius:999px;background:var(--surface2);color:var(--muted);margin-right:4px}
.paper-head{position:sticky;top:57px;z-index:20;background:var(--bg);border-bottom:1px solid var(--line);padding:10px 0;display:flex;gap:12px;align-items:center;flex-wrap:wrap}
.q{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);padding:14px 18px;margin:16px 0;scroll-margin-top:130px}
.q>header{font-size:.78rem;text-transform:uppercase;letter-spacing:.07em;color:var(--muted);font-weight:700;margin-bottom:8px;display:flex;gap:8px;flex-wrap:wrap;align-items:center}
.qbody img,.opts img{max-width:100%;vertical-align:middle}
.qbody p{margin:.5em 0}
.ctx{background:var(--surface2);border:1px dashed var(--line);border-radius:12px;padding:10px 14px;margin:10px 0}
.ctx .ctxl{font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:800}
ol.opts{list-style:none;margin:10px 0 0;padding:0;counter-reset:o}
ol.opts li{counter-increment:o;display:block;overflow-x:auto;border:1px solid var(--line);border-radius:10px;padding:8px 12px;margin:7px 0;cursor:pointer;background:var(--bg)}
ol.opts li::before{content:counter(o,upper-alpha)".";display:inline-block;font-weight:800;color:var(--muted);min-width:1.6em;margin-right:6px}
ol.opts li img{max-width:100%;height:auto}
ol.opts li:hover{border-color:var(--acc)}
ol.opts li.sel{border-color:var(--acc);box-shadow:inset 0 0 0 1px var(--acc)}
ol.opts li.right{background:var(--okbg);border-color:var(--ok)}
ol.opts li.wrong{background:var(--badbg);border-color:var(--bad)}
.numin{margin-top:10px}
.numin input{padding:8px 12px;border:1px solid var(--line);border-radius:10px;background:var(--bg);color:var(--text);font:inherit;width:200px}
.fb{display:none;margin-top:10px;padding:8px 12px;border-radius:10px;font-size:.92rem}
.fb.show{display:block}
.fb.good{background:var(--okbg);color:var(--ok)} .fb.bad{background:var(--badbg);color:var(--bad)} .fb.nokey{background:var(--surface2);color:var(--muted)}
.scorebox{background:var(--surface);border:2px solid var(--acc);border-radius:var(--radius);padding:14px 18px;margin:16px 0;display:none}
.scorebox.show{display:block}
.keysec{display:none}
.heat td,.heat th{text-align:center;padding:6px 8px;font-variant-numeric:tabular-nums}
.heat td:first-child,.heat th:first-child{text-align:left}
.hbar{display:inline-block;height:9px;border-radius:5px;background:var(--acc);vertical-align:middle;margin-right:6px;min-width:2px}
.insight{background:var(--surface);border:1px solid var(--line);border-left:5px solid var(--acc);border-radius:12px;padding:12px 18px;margin:14px 0}
footer.foot{border-top:1px solid var(--line);margin-top:60px;padding:22px 0;color:var(--muted);font-size:.88rem}


/* ================= hardening: every screen, no visible scrollbars, nothing clipped ================= */
*{scrollbar-width:none;-ms-overflow-style:none}
*::-webkit-scrollbar{display:none;width:0;height:0}
html{-webkit-text-size-adjust:100%;text-size-adjust:100%}
body{overflow-x:clip;overflow-wrap:anywhere}
article,.card,.callout,.q,.insight,.quiz,.widget-box,figure,td,th,li,p,h1,h2,h3,h4,summary,blockquote,.chip,.official,.needs,.pill,.out{min-width:0;overflow-wrap:anywhere}
img,svg,video,canvas,iframe{max-width:100%}
img{height:auto}
pre{overflow:visible;white-space:break-spaces;word-break:break-word;overflow-wrap:anywhere}
pre code{white-space:break-spaces;word-break:break-word}
.katex-display>.katex.wrapmath{white-space:normal}
.katex-display>.katex.wrapmath>.katex-html{display:block}
.tablewrap{overflow:visible}
.mathblock{overflow:visible}
.mathblock .katex-display{margin:0}
ol.opts li{overflow:visible}
.nav{overflow:visible}
.widget input[type=range]{width:min(220px,100%)}
.widget .row{min-width:0}
.numin input{width:min(220px,100%)}
.pager a{min-width:min(200px,100%)}
.bigcta a{min-width:min(260px,100%)}
.stat div{min-width:min(100px,100%)}
.side,.toc{overflow:visible;max-height:none}
.side a,.toc a{overflow-wrap:anywhere}
.brand{white-space:normal}
.menubtn{display:none}
.brand{order:1} .nav{order:2;flex:1 1 auto;min-width:0} .tools{order:3;min-width:0}
#q{flex:1 1 120px;min-width:0;width:170px;max-width:100%}
.hero h1{font-size:clamp(1.9rem,5.2vw,2.9rem);max-width:none}
:root{--hdr:57px}
.paper-head{top:var(--hdr)}
article h2,article h3,.q{scroll-margin-top:calc(var(--hdr) + 18px)}
.side,.toc{top:calc(var(--hdr) + 16px)}

/* sticky side panels only when the screen is tall enough to show them whole */
@media (min-width:1101px) and (max-height:759px){.side,.toc{position:static}}

/* large and ultra-wide screens: use the space, scale type */
@media (min-width:1700px){
  body{font-size:18.5px}
  .wrap,.top-in{max-width:1560px}
  .lesson-layout{grid-template-columns:280px minmax(0,1fr) 240px}
}
@media (min-width:2300px){
  body{font-size:21px}
  .wrap,.top-in{max-width:1960px}
  .lesson-layout{grid-template-columns:320px minmax(0,1fr) 280px;gap:48px}
  .cards{grid-template-columns:repeat(auto-fit,minmax(min(380px,100%),1fr))}
}
@media (min-width:3200px){
  body{font-size:25px}
  .wrap,.top-in{max-width:2600px}
}

/* tablets and below: menu button instead of a long nav bar */
@media (max-width:1320px){
  .menubtn{display:inline-flex;align-items:center}
  .nav{display:none;order:4;flex:1 1 100%;flex-direction:column;gap:2px;padding:6px 0 2px}
  .nav.open{display:flex}
  .nav a{white-space:normal;padding:10px 14px;border-radius:12px;font-size:1rem}
  .tools{order:2;margin-left:auto;flex:1 1 230px;justify-content:flex-end;flex-wrap:wrap}
  #results{right:14px;left:14px;width:auto;max-width:560px;margin-left:auto}
}

.tablewrap.stack table,.tablewrap.stack thead,.tablewrap.stack tbody,.tablewrap.stack tr,.tablewrap.stack th,.tablewrap.stack td{display:block;width:100%;min-width:0}
.tablewrap.stack thead{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0)}
.tablewrap.stack tr{border:1px solid var(--line);border-radius:12px;margin:0 0 10px;padding:4px 12px;background:var(--surface)}
.tablewrap.stack td{border:0;border-bottom:1px dashed var(--line);padding:8px 0}
.tablewrap.stack td:last-child{border-bottom:0}
.tablewrap.stack td[data-label]::before{content:attr(data-label);display:block;font-size:.7rem;text-transform:uppercase;letter-spacing:.07em;color:var(--muted);font-weight:700;margin-bottom:2px}
.tablewrap.stack td[data-label=""]::before{display:none}

/* phones: stack every table into labelled cards so nothing is cut off or scrolls sideways */
@media (max-width:700px){
  .callout,.quiz,.widget-box,.insight,.q{padding-left:14px;padding-right:14px}
  .tools{flex:1 1 100%;justify-content:stretch}
  #q{flex:1 1 140px}
}
@media (max-width:700px){
  .tablewrap table{display:block}
}
@media (max-width:430px){
  body{font-size:16px}
  .wrap{padding:12px 12px 48px}
  .top-in{padding:8px 12px}
  article h1{font-size:1.45rem}
  article h2{font-size:1.25rem}
  .meta-row{gap:6px}
  .chip{font-size:.78rem;padding:3px 10px}
  .btn,.qcheck{padding:9px 14px}
  .pager a{flex:1 1 100%}
  .wk{gap:4px}
  .wk a{padding:7px 0;font-size:.85rem}
}
@media (max-width:340px){
  body{font-size:15.5px}
  .wrap{padding:10px 10px 40px}
  .hero h1{font-size:1.7rem}
  .callout,.quiz,.widget-box,.insight,.q{padding-left:11px;padding-right:11px}
  .wk{grid-template-columns:repeat(4,1fr)}
}

/* equation/code screenshots are dark-on-white pictures: flip them in dark mode */
@media (prefers-color-scheme:dark){
  :root:not([data-theme=light]) .qbody img,:root:not([data-theme=light]) .opts img,:root:not([data-theme=light]) .ctx img{filter:invert(.9) hue-rotate(180deg)}
}
:root[data-theme=dark] .qbody img,:root[data-theme=dark] .opts img,:root[data-theme=dark] .ctx img{filter:invert(.9) hue-rotate(180deg)}

/* ---------- responsive ---------- */
@media (max-width:1100px){
  .lesson-layout{grid-template-columns:230px minmax(0,1fr)}
  .toc{display:none}
}
@media (max-width:820px){
  .top{position:static}
  .top-in{padding:8px 14px;gap:8px}
  .tools{margin-left:auto}
  #results{top:48px;right:14px}
  .paper-head{top:0}
  .q{scroll-margin-top:70px}
  body{font-size:16.5px}
  .wrap{padding:14px 16px 60px}
  .lesson-layout{grid-template-columns:1fr}
  .side{position:static;max-height:none;display:none;margin-bottom:12px;background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:10px}
  .side.open{display:block}
  .weeks-btn{display:inline-flex;margin:0 0 12px}
  .hero h1{font-size:2rem}
  article h1{font-size:1.65rem}
}

/* ---------- print (also used for PDF export of papers) ---------- */
@media print{
  img{filter:none!important}
  :root{--bg:#fff;--surface:#fff;--surface2:#f3f3f3;--text:#111;--muted:#555;--line:#cfcfcf}
  body{font-size:11pt;line-height:1.45;background:#fff;color:#111}
  .crumb,.meta-row a.chip,.top,.side,.toc,.pager,.donebar,.paper-head,.weeks-btn,.scorebox,footer.foot,.noprint,.fb,.numin input{display:none!important}
  .wrap{max-width:none;padding:0}
  .q{break-inside:avoid;page-break-inside:avoid;box-shadow:none;border:0;border-left:3px solid #666;border-radius:0;margin:12px 0;padding:6px 12px}
  ol.opts li{border:0;padding:2px 0;margin:2px 0 2px 16px;background:none}
  .keysec{display:block;page-break-before:always}
  .keysec li.ans{font-weight:700}
  .callout,.insight{break-inside:avoid}
  a{color:inherit;text-decoration:none}
  details>*{display:block!important}
  .summary{page-break-before:always}
  @page{size:A4;margin:14mm}
}

/* ===== kid-friendly layer (fun.js) ===== */
.vidbox{margin:1.2rem 0 1.6rem;padding:14px;border-radius:20px;background:linear-gradient(135deg,#ffe8f1,#e6f0ff 55%,#e3fbef);border:2px solid #ffffff;box-shadow:0 8px 28px rgba(80,60,160,.16);color:#241a4a;min-width:0}
.vidbox .vid-head{display:flex;gap:12px;align-items:center;margin-bottom:10px}
.vidbox .vid-head small{display:block;color:#5b5480;font-size:.88rem}
.vid-ico{font-size:2rem;animation:bob 2.2s ease-in-out infinite}
.vidbox video{display:block;width:100%;max-width:100%;height:auto;aspect-ratio:16/9;border-radius:14px;background:#111}
.vid-script{margin-top:10px}.vid-script summary{cursor:pointer;font-weight:700}
.vid-script ol{padding-left:1.3rem;margin:.6rem 0 0}.vid-script li{margin:.5rem 0}
.vgrid{display:grid;grid-template-columns:repeat(auto-fill,minmax(min(100%,240px),1fr));gap:16px;margin:1.4rem 0}
.vcard{position:relative;display:flex;flex-direction:column;gap:6px;padding:10px 10px 14px;border-radius:18px;background:#fff;border:2px solid #e5e0f5;text-decoration:none;color:#241a4a;transition:transform .2s,box-shadow .2s;min-width:0}
.vcard:hover,.vcard:focus-visible{transform:translateY(-5px) rotate(-.6deg);box-shadow:0 12px 26px rgba(80,60,160,.22)}
.vcard img{width:100%;height:auto;aspect-ratio:16/9;object-fit:cover;border-radius:12px;display:block}
.vcard .vtag{font-size:.78rem;font-weight:800;text-transform:uppercase;letter-spacing:.04em;color:#6b6490}
.vcard .play{position:absolute;right:18px;top:calc(10px + 38%);width:44px;height:44px;margin-top:-22px;border-radius:50%;display:grid;place-items:center;background:#ff5e7e;color:#fff;box-shadow:0 4px 12px rgba(0,0,0,.3);transition:transform .2s}
.vcard:hover .play{transform:scale(1.15)}
@keyframes bob{0%,100%{transform:translateY(0)}50%{transform:translateY(-5px)}}
@keyframes wob{0%,100%{transform:rotate(0)}25%{transform:rotate(-8deg)}75%{transform:rotate(8deg)}}
@keyframes fall{to{transform:translateY(105vh) rotate(720deg);opacity:.9}}
@keyframes shk{0%,100%{transform:translateX(0)}20%,60%{transform:translateX(-7px)}40%,80%{transform:translateX(7px)}}
.confetti{position:fixed;inset:0;pointer-events:none;z-index:300;overflow:hidden}
.confetti i{position:absolute;top:-14px;width:9px;height:14px;border-radius:2px;animation:fall 2.4s linear forwards}
.shake{animation:shk .5s}
.pip-dock{position:fixed;right:14px;bottom:14px;z-index:90;display:flex;align-items:flex-end;gap:8px;max-width:calc(100vw - 28px)}
.pip-dock button{width:48px;height:48px;border-radius:50%;border:2px solid #fff;background:#7c5cff;color:#fff;font-size:1.5rem;line-height:1;cursor:pointer;box-shadow:0 6px 16px rgba(0,0,0,.28);display:grid;place-items:center;padding:0;transition:transform .15s}
.pip-dock button:hover{transform:scale(1.1) rotate(-6deg)}
.pip-dock .pip span{display:block;animation:wob 3.5s ease-in-out infinite}
.pip-dock .snd{background:#14b8a6;width:40px;height:40px;font-size:1.1rem}
.pip-bubble{position:absolute;right:0;bottom:58px;width:min(260px,calc(100vw - 28px));padding:10px 12px;border-radius:14px;background:#fff;color:#241a4a;border:2px solid #7c5cff;font-size:.92rem;line-height:1.4;box-shadow:0 8px 22px rgba(0,0,0,.25)}
.pip-bubble[hidden]{display:none}
.rv{opacity:0;transform:translateY(16px);transition:opacity .5s,transform .5s}
.rv.in{opacity:1;transform:none}
@media (hover:hover){.btn:hover,.chip:hover{transform:translateY(-2px) scale(1.03)}}
.btn,.chip,.nav a,ol.opts li{transition:transform .15s,background-color .2s,box-shadow .2s}
ol.opts li:active{transform:scale(.98)}
.hero h1{background:linear-gradient(90deg,#ff5e7e,#ffb100,#2fc27b,#3b82f6,#a855f7);-webkit-background-clip:text;background-clip:text;color:transparent;background-size:200% auto;animation:shine 8s linear infinite}
@keyframes shine{to{background-position:200% center}}
@media (prefers-reduced-motion:reduce){*{animation:none!important;transition:none!important}.rv{opacity:1;transform:none}}
@media print{.pip-dock,.confetti,.vidbox video{display:none!important}.rv{opacity:1;transform:none}}

.lesson-layout.together{grid-template-columns:minmax(0,1fr) 210px}
@media (max-width:1100px){.lesson-layout.together{grid-template-columns:minmax(0,1fr)}}

/* ===== viva ===== */
.callout.viva{border-left:6px solid #7c5cff;background:#f1edff;color:#241a4a}
:root[data-theme=dark] .callout.viva{background:#2a2450;color:#eee9ff}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]) .callout.viva{background:#2a2450;color:#eee9ff}}
details.vq{margin:10px 0;border:2px solid var(--line,#e5e0f5);border-radius:14px;background:var(--surface,#fff);overflow:hidden}
details.vq>summary{cursor:pointer;padding:12px 14px;font-weight:700;list-style:none;display:flex;gap:10px;align-items:baseline;flex-wrap:wrap}
details.vq>summary::-webkit-details-marker{display:none}
details.vq[open]>summary{background:rgba(124,92,255,.12)}
details.vq.known{border-color:#2fc27b}
.vqn{display:inline-grid;place-items:center;min-width:2em;height:2em;padding:0 .4em;border-radius:99px;background:#7c5cff;color:#fff;font-size:.8rem}
.va{padding:4px 14px 12px}
.va pre{max-width:100%}
details.vq .vknow{margin:0 14px 14px}
.chip.vf{cursor:pointer;font:inherit}
.chip.vf.on{background:#7c5cff;color:#fff;border-color:#7c5cff}
.mockbox{padding:16px;border:2px solid var(--line,#e5e0f5);border-radius:18px;background:var(--surface,#fff);min-width:0}
.mockset{display:flex;flex-wrap:wrap;gap:10px 16px;align-items:center}
.mockset label{display:flex;gap:6px;align-items:center;flex-wrap:wrap}
.mockset select{font:inherit;padding:6px 8px;border-radius:8px;max-width:100%}
.mtop{display:flex;justify-content:space-between;gap:10px;flex-wrap:wrap;color:var(--muted)}
.mq h2{margin:.6em 0}
.mbtns{display:flex;gap:10px;flex-wrap:wrap;margin-top:12px}
details.ocrtxt{margin:6px 0;font-size:.85rem}
details.ocrtxt summary{cursor:pointer;color:var(--muted)}
details.ocrtxt pre{margin:6px 0;max-width:100%}

/* ===== MAD subject accents ===== */
body[data-subject=mad1]{--acc:#b45f06} body[data-subject=mad2]{--acc:#1f7a5c}
.card.mad1{border-top:4px solid #b45f06} .card.mad2{border-top:4px solid #1f7a5c}
:root[data-theme=dark] body[data-subject=mad1]{--acc:#e8a85a} :root[data-theme=dark] body[data-subject=mad2]{--acc:#5fc3a0}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]) body[data-subject=mad1]{--acc:#e8a85a} :root:not([data-theme=light]) body[data-subject=mad2]{--acc:#5fc3a0}}
.mockset label{min-width:0;max-width:100%}
.mockset select{max-width:100%;min-width:0}
@media (max-width:560px){.mockset label{display:flex;flex-direction:column;align-items:stretch;width:100%}.mockset select{width:100%}}