/* ITProstuti web design — independent of the PDF books' style.css. Light by default; dark via [data-theme=dark]. */
:root{
  --bg:#f7f6f2;--surface:#fff;--sunk:#f0eee8;--ink:#1c2321;--muted:#5f6b66;--line:#e3e0d8;--line-2:#d3cfc4;
  --brand:#0b7a55;--brand-ink:#075c40;--brand-soft:#e3f3ec;--accent:#0b7a55;
  --red:#d6404e;--red-soft:#fdecee;--amber:#b86e00;--amber-soft:#fff4dc;--blue:#2563eb;--blue-soft:#e9f0ff;
  --violet:#6d4fd8;--violet-soft:#f0ecff;--teal:#0f8a7e;--teal-soft:#e2f5f2;--code:#f3f1ec;
  --top:60px;--radius:14px;--shadow:0 1px 2px rgba(20,30,25,.05),0 4px 16px rgba(20,30,25,.05);
  --sans:'Inter','Hind Siliguri','Noto Sans Math','Noto Sans Symbols','Noto Sans Symbols 2',system-ui,sans-serif;
  --mono:'JetBrains Mono','Hind Siliguri','Noto Sans Math','Noto Sans Symbols 2',ui-monospace,monospace}
[data-theme=dark]{
  --bg:#0c1311;--surface:#121b18;--sunk:#0f1714;--ink:#e4ebe8;--muted:#9aa8a2;--line:#22302b;--line-2:#2d3d37;
  --brand:#34c28e;--brand-ink:#5fd8a9;--brand-soft:#123327;--accent:#4ccf9c;
  --red:#ff7a85;--red-soft:#3a1a1e;--amber:#f0b14a;--amber-soft:#33270f;--blue:#7aa5ff;--blue-soft:#17233d;
  --violet:#ab97ff;--violet-soft:#221c3d;--teal:#4fd1c1;--teal-soft:#0f2e2a;--code:#18231f;
  --shadow:0 1px 2px rgba(0,0,0,.3);color-scheme:dark}
[lang=bn]{--sans:'Hind Siliguri','Inter','Noto Sans Math','Noto Sans Symbols','Noto Sans Symbols 2',system-ui,sans-serif}
*{box-sizing:border-box}
[hidden]{display:none!important}
html{scroll-padding-top:calc(var(--top) + 16px);-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:16.5px/1.72 var(--sans);font-feature-settings:"cv11","ss01"}
[lang=bn] body{font-size:17.5px}
a{color:var(--accent);text-underline-offset:3px}
button{font:inherit;color:inherit;cursor:pointer}
img,svg{max-width:100%}
.eyebrow{margin:0;font-size:.78rem;font-weight:700;letter-spacing:.08em;text-transform:uppercase;color:var(--c,var(--brand))}
.btn{display:inline-flex;align-items:center;background:var(--brand);color:#fff;text-decoration:none;border-radius:999px;
  padding:9px 18px;font-weight:600;font-size:.93rem;border:1px solid transparent}
.btn:hover{filter:brightness(1.08)}
.btn.ghost{background:transparent;color:var(--ink);border-color:var(--line-2)}
.btn.ghost:hover{border-color:var(--brand);color:var(--brand)}
[data-theme=dark] .btn:not(.ghost){color:#06251a}
h2.plain{font-size:1.25rem;margin:40px 0 14px}

/* top bar */
.top{position:sticky;top:0;z-index:20;height:var(--top);display:flex;align-items:center;gap:10px;padding:0 20px;
  background:color-mix(in srgb,var(--bg) 85%,transparent);backdrop-filter:blur(10px);border-bottom:1px solid var(--line)}
.brand{font-weight:800;font-size:1.1rem;color:var(--ink);text-decoration:none;display:flex;align-items:center;gap:8px;letter-spacing:-.01em}
.mark{display:grid;place-items:center;width:30px;height:30px;border-radius:9px;background:var(--brand);color:#fff;font:700 1rem 'Hind Siliguri',sans-serif}
.crumb{color:var(--muted);text-decoration:none;font-weight:500;font-size:.92rem;white-space:nowrap;overflow:hidden;text-overflow:ellipsis;min-width:0}
.crumb::before{content:"›";margin:0 8px 0 2px;color:var(--line-2)}
.grow{flex:1}
.top .auth{padding:6px 14px;font-size:.85rem;flex:none;white-space:nowrap}
.login .google{margin:8px 0}
@media (max-width:480px){.top .auth{padding:5px 10px;font-size:.8rem}.top .brand{font-size:0;gap:0}}  /* room for Log in on small phones: logo mark only */
.icon{background:var(--surface);border:1px solid var(--line);border-radius:10px;width:38px;height:38px;display:grid;place-items:center;flex:none;color:var(--muted)}
.icon:hover{color:var(--ink);border-color:var(--line-2)}
.menu{display:none}
.lang{display:flex;background:var(--sunk);border:1px solid var(--line);border-radius:999px;padding:3px;flex:none}
.lang a{padding:3px 11px;border-radius:999px;text-decoration:none;color:var(--muted);font-size:.85rem;font-weight:600}
.lang a[aria-current]{background:var(--surface);color:var(--ink);box-shadow:var(--shadow)}

/* reading layout */
.layout{display:grid;grid-template-columns:272px minmax(0,1fr) 220px;max-width:1440px;margin:0 auto}
.side,.toc-side{position:sticky;top:var(--top);height:calc(100vh - var(--top));overflow-y:auto;padding:22px 14px 30px}
.side-h{font-size:.72rem;text-transform:uppercase;letter-spacing:.08em;color:var(--muted);font-weight:700;margin:6px 10px 8px}
.nav{list-style:none;margin:0 0 22px;padding:0;font-size:.9rem}
.nav a{display:flex;gap:10px;align-items:flex-start;padding:6px 10px;border-radius:9px;text-decoration:none;color:var(--ink);line-height:1.4}
.nav a:hover{background:var(--sunk)}
.nav a[aria-current]{background:var(--brand-soft);color:var(--brand-ink);font-weight:600}
.nav small{color:var(--muted);margin-left:auto}
.dot{flex:none;width:14px;height:14px;margin-top:3px;border-radius:50%;border:2px solid var(--line-2)}
.is-done .dot{background:var(--brand);border-color:var(--brand);box-shadow:inset 0 0 0 2px var(--surface)}
.toc-side ol{list-style:none;margin:0;padding:0 0 0 10px;border-left:1px solid var(--line);font-size:.83rem}
.toc-side a{display:block;padding:4px 10px;text-decoration:none;color:var(--muted);line-height:1.4;margin-left:-11px;border-left:2px solid transparent}
.toc-side a:hover{color:var(--ink)}
.toc-side a.on{color:var(--brand-ink);border-left-color:var(--brand);font-weight:600}
.main{min-width:0;padding:28px 48px 0}
.progress{height:6px;border-radius:99px;background:var(--sunk);overflow:hidden;margin:8px 0}
.progress span{display:block;height:100%;width:0;background:var(--c,var(--brand));border-radius:99px;transition:width .4s}
.progress.small{margin:0 10px 14px}

/* chapter header */
.ch-head{max-width:780px;margin:0 auto 10px;padding-bottom:18px;border-bottom:1px solid var(--line)}
.ch-head h1{font-size:2.15rem;line-height:1.2;letter-spacing:-.02em;margin:6px 0 8px}
[lang=bn] .ch-head h1{letter-spacing:0;line-height:1.35}
.meta{color:var(--muted);font-size:.88rem;margin:0}
.ch-tools{display:flex;align-items:center;gap:12px;margin-top:14px;flex-wrap:wrap}
.modes{display:inline-flex;background:var(--sunk);border:1px solid var(--line);border-radius:999px;padding:3px}
.modes button{border:0;background:none;padding:5px 14px;border-radius:999px;font-size:.88rem;font-weight:600;color:var(--muted)}
[data-mode=study] [data-set-mode=study],[data-mode=practice] [data-set-mode=practice]{background:var(--surface);color:var(--ink);box-shadow:var(--shadow)}
.score{font-size:.88rem;font-weight:600;color:var(--brand-ink);background:var(--brand-soft);border-radius:999px;padding:4px 12px}

/* prose: notes content rendered as web article */
.prose{max-width:780px;margin:0 auto}
.prose h2{font-size:1.5rem;line-height:1.3;letter-spacing:-.01em;margin:48px 0 14px}
.prose h3{font-size:1.15rem;line-height:1.4;margin:30px 0 10px}
.prose h2 .hl,.prose h3 .hl{color:inherit;text-decoration:none}
.prose h2 .hl:hover::after,.prose h3 .hl:hover::after{content:" #";color:var(--line-2)}
.num{display:inline-block;font-size:.72em;font-weight:700;color:var(--brand-ink);background:var(--brand-soft);border-radius:8px;padding:1px 8px;margin-right:10px;vertical-align:.12em}
.prose p{margin:12px 0}
.prose ul,.prose ol{padding-left:24px;margin:10px 0}
.prose li{margin:5px 0}
.prose li::marker{color:var(--muted)}
.chap-en{color:var(--muted);font-weight:500;margin:14px 0}
.small,.cap{font-size:.86rem;color:var(--muted)}
.cap{text-align:center;margin:-4px 0 18px}
.two{display:grid;grid-template-columns:1fr 1fr;gap:16px}
.two>*{min-width:0}  /* let wide <pre> scroll inside its column instead of widening the page */
.prose :is(p,li,.box)>:is(code,b),.prose p.small,.quiz .opt{overflow-wrap:anywhere}  /* long IPs, paths, hostnames wrap on phones (tables keep scrolling) */
.tw{overflow-x:auto;margin:18px 0;border:1px solid var(--line);border-radius:12px;background:var(--surface)}
table{width:100%;border-collapse:collapse;font-size:.92rem}
th{text-align:left;font-weight:600;font-size:.82rem;letter-spacing:.02em;color:var(--muted);background:var(--sunk);padding:10px 14px;border-bottom:1px solid var(--line)}
td{padding:10px 14px;border-bottom:1px solid var(--line);vertical-align:top}
tr:last-child td{border-bottom:0}
code,.mono{font-family:var(--mono);font-size:.86em;background:var(--code);padding:1px 5px;border-radius:5px;font-variant-ligatures:none}
pre{font-family:var(--mono);font-size:.86rem;line-height:1.6;background:#0f1a17;color:#dbe7e2;padding:16px 18px;border-radius:12px;overflow-x:auto;
  white-space:pre;font-variant-ligatures:none;margin:16px 0}
pre code{background:none;padding:0;color:inherit}
.diagram{margin:22px 0 8px;padding:16px;background:#fff;border:1px solid var(--line);border-radius:var(--radius);text-align:center;overflow-x:auto}
.diagram svg{height:auto}
[data-theme=dark] .diagram{border-color:transparent}

/* callouts */
.box{position:relative;margin:20px 0;padding:14px 18px;border-radius:var(--radius);background:var(--sunk);border:1px solid var(--line)}
.box .bt{display:flex;align-items:center;gap:8px;flex-wrap:wrap;font-weight:700;font-size:.9rem;margin-bottom:4px}
.box>:last-child{margin-bottom:0}
.ex{background:var(--amber-soft);border-color:transparent}.ex .bt{color:var(--amber)}
.th{background:var(--red-soft);border-color:transparent}.th .bt{color:var(--red)}
.warn{background:var(--red-soft);border-color:transparent}.warn .bt{color:var(--red)}
.tip{background:var(--teal-soft);border-color:transparent}.tip .bt{color:var(--teal)}
.fm{background:var(--violet-soft);border-color:transparent;text-align:center;font-weight:600;font-family:var(--mono);font-size:.95rem}
.pq{background:var(--surface);border:1px solid var(--line);border-left:4px solid var(--blue);box-shadow:var(--shadow)}
.pq .bt{color:var(--blue);font-size:.95rem}
.pq i{font-style:normal;font-weight:500}
.src{font-size:.72rem;font-weight:600;letter-spacing:.02em;color:var(--muted);background:var(--sunk);border:1px solid var(--line);border-radius:999px;padding:1px 9px}

/* hideable answers (practice mode) */
.answer{position:relative}
.reveal{display:none}
[data-mode=practice] .answer:not(.shown)>*{display:none}
[data-mode=practice] .answer:not(.shown) .reveal{display:inline-flex}
.reveal{margin:10px 0 18px;border:1px dashed var(--line-2);background:var(--surface);border-radius:999px;padding:7px 16px;font-size:.9rem;font-weight:600;color:var(--brand-ink)}
.reveal:hover{border-color:var(--brand)}

/* interactive MCQ */
.quiz{margin:16px 0;padding:16px 18px;background:var(--surface);border:1px solid var(--line);border-radius:var(--radius)}
.quiz .q{font-weight:600;margin-bottom:10px}
.quiz .opts{display:grid;grid-template-columns:1fr 1fr;gap:8px}
.opt{text-align:left;background:var(--bg);border:1px solid var(--line);border-radius:10px;padding:8px 12px;line-height:1.45}
.opt:hover:not(:disabled){border-color:var(--brand)}
.opt:disabled{cursor:default;color:inherit}
.opt.right{background:var(--brand-soft);border-color:var(--brand);color:var(--brand-ink);font-weight:600}
.opt.wrong{background:var(--red-soft);border-color:var(--red);color:var(--red)}
.opt.picked{border-color:var(--blue);background:var(--blue-soft)}
.explain{margin-top:10px;font-size:.92rem;color:var(--muted)}
[data-mode=practice] .quiz:not(.answered) .explain{display:none}

.done{display:flex;margin:36px auto 0;max-width:780px;width:100%;justify-content:center;border:1px dashed var(--line-2);background:var(--surface);
  border-radius:var(--radius);padding:14px;font-weight:600;color:var(--muted)}
.done:hover{border-color:var(--brand);color:var(--brand-ink)}
.done.on{background:var(--brand-soft);border:1px solid var(--brand);color:var(--brand-ink)}

/* prev / next + footer */
.pn{max-width:780px;margin:20px auto 0;display:grid;grid-template-columns:1fr 1fr;gap:12px}
.pn a{border:1px solid var(--line);border-radius:var(--radius);padding:12px 16px;text-decoration:none;color:var(--ink);background:var(--surface);line-height:1.4;font-weight:600}
.pn a:hover{border-color:var(--brand)}
.pn small{display:block;color:var(--muted);font-weight:500;margin-bottom:2px}
.pn .next{text-align:right;grid-column:2}
.foot{max-width:780px;margin:48px auto 0;padding:22px 0 40px;border-top:1px solid var(--line);color:var(--muted);font-size:.86rem}
.foot p{margin:4px 0}

/* course page */
.course .main .prose,.course .main h2.plain,.course .ch-grid{max-width:980px}
.course .main h2.plain{margin-left:auto;margin-right:auto}
.course-hero{max-width:980px;margin:0 auto;padding:34px;border-radius:22px;background:var(--surface);border:1px solid var(--line);
  background-image:radial-gradient(circle at 100% 0,color-mix(in srgb,var(--c) 16%,transparent),transparent 55%)}
.course-hero h1{font-size:2.3rem;line-height:1.15;letter-spacing:-.02em;margin:8px 0 10px}
.course-hero p{margin:4px 0;color:var(--muted)}
.tags{list-style:none;display:flex;flex-wrap:wrap;gap:8px;padding:0;margin:16px 0}
.tags li{font-size:.82rem;background:var(--sunk);border:1px solid var(--line);border-radius:999px;padding:3px 12px}
.course-hero .progress{max-width:360px;margin:18px 0 6px}
.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:16px}
.ch-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(240px,1fr));gap:12px;margin:0 auto}
.ch-card{position:relative;display:flex;flex-direction:column;gap:4px;padding:16px 18px;border-radius:var(--radius);background:var(--surface);
  border:1px solid var(--line);text-decoration:none;color:var(--ink);line-height:1.35}
.ch-card:hover{border-color:var(--brand);box-shadow:var(--shadow)}
.ch-card .eb{font-size:.74rem;font-weight:700;color:var(--brand-ink);text-transform:uppercase;letter-spacing:.06em}
.ch-card small{color:var(--muted);margin-top:auto;padding-top:6px}
.ch-card.is-done::after{content:"✓";position:absolute;top:12px;right:14px;width:22px;height:22px;border-radius:50%;background:var(--brand);color:#fff;
  display:grid;place-items:center;font-size:.75rem}

/* home */
.home{max-width:1120px;margin:0 auto;padding:0 20px}
.home-hero{padding:72px 0 36px;max-width:760px}
.home-hero h1{font-size:3rem;line-height:1.08;letter-spacing:-.035em;margin:12px 0 16px}
.lede{font-size:1.15rem;color:var(--muted);margin:0}
.search-big{margin-top:26px;width:min(560px,100%);display:flex;justify-content:space-between;align-items:center;padding:14px 18px;
  border:1px solid var(--line-2);border-radius:14px;background:var(--surface);color:var(--muted);box-shadow:var(--shadow);font-size:1rem}
.search-big:hover{border-color:var(--brand)}
kbd{border:1px solid var(--line-2);border-bottom-width:2px;border-radius:6px;padding:0 7px;font:600 .8rem var(--mono)}
.continue{display:flex;align-items:center;gap:14px;flex-wrap:wrap;padding:14px 18px;margin-bottom:16px;border-radius:var(--radius);background:var(--brand-soft);color:var(--brand-ink)}
.continue a{font-weight:700;color:inherit}
.latest{padding:18px 22px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line)}
.latest h2{font-size:1rem;margin:0 0 8px}
.latest ul{list-style:none;margin:0;padding:0}
.latest a{display:flex;gap:10px;align-items:center;padding:6px 0;text-decoration:none;color:var(--ink);font-weight:500}
.latest a:hover{color:var(--brand-ink)}
.new{font-size:.66rem;font-weight:800;letter-spacing:.06em;color:#fff;background:var(--red);border-radius:6px;padding:1px 6px}
.tracks{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:16px}
.track{display:flex;flex-direction:column;padding:22px;border-radius:18px;background:var(--surface);border:1px solid var(--line);border-top:4px solid var(--c)}
.track h3{margin:6px 0 6px;font-size:1.15rem;line-height:1.3}
.track>p{margin:0 0 8px;color:var(--muted);font-size:.93rem}
.track .meta{margin-top:auto}
.btns{display:flex;gap:8px;flex-wrap:wrap;margin-top:12px}
.btns .btn{background:var(--c,var(--brand));padding:7px 16px}
.btns .btn.ghost{background:transparent}
.how{display:grid;grid-template-columns:repeat(3,1fr);gap:16px;margin-top:40px}
.how div{padding:18px;border-radius:var(--radius);background:var(--sunk)}
.how p{margin:4px 0 0;color:var(--muted);font-size:.93rem}

/* search dialog (Pagefind UI) */
.search{width:min(760px,calc(100% - 24px));max-height:80vh;border:1px solid var(--line);border-radius:18px;padding:22px;
  background:var(--surface);color:var(--ink);margin-top:8vh;box-shadow:0 20px 60px rgba(0,0,0,.25)}
.search::backdrop{background:rgba(8,14,12,.5);backdrop-filter:blur(2px)}
.search .close{position:absolute;top:6px;right:12px;background:none;border:0;font-size:1.6rem;color:var(--muted)}
.search{--pagefind-ui-primary:var(--brand);--pagefind-ui-text:var(--ink);--pagefind-ui-background:var(--surface);
  --pagefind-ui-border:var(--line-2);--pagefind-ui-tag:var(--sunk);--pagefind-ui-font:var(--sans);--pagefind-ui-border-radius:10px}


/* header links + drawer quick links */
.links{display:flex;gap:4px;margin-left:10px}
.links a{padding:6px 12px;border-radius:999px;text-decoration:none;color:var(--muted);font-weight:600;font-size:.9rem}
.links a:hover{color:var(--ink);background:var(--sunk)}
.quick{display:none}

/* home: practice call-to-action */
.practise-cta{display:flex;align-items:center;justify-content:space-between;gap:16px;flex-wrap:wrap;margin-top:16px;padding:20px 22px;
  border-radius:var(--radius);background:var(--surface);border:1px solid var(--line);border-left:4px solid var(--amber)}
.practise-cta h2{font-size:1.1rem;margin:0}
.practise-cta p{margin:2px 0 0;color:var(--muted)}
.practise-cta .btns{margin:0}
.practise-cta .btn{background:var(--brand)}
.practise-cta .btn.ghost{background:transparent}

/* practice page */
.setup{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:14px;padding:22px;border-radius:18px;background:var(--surface);border:1px solid var(--line)}
.setup label{display:flex;flex-direction:column;gap:6px;font-size:.85rem;font-weight:600;color:var(--muted)}
.setup select{font:inherit;color:var(--ink);background:var(--bg);border:1px solid var(--line-2);border-radius:10px;padding:9px 10px}
.setup-actions{grid-column:1/-1;display:flex;gap:10px;flex-wrap:wrap}
.runbar{position:sticky;top:calc(var(--top) + 8px);z-index:5;display:flex;align-items:center;gap:16px;padding:10px 12px 10px 20px;margin-bottom:10px;
  border-radius:999px;background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow)}
.runbar b{font:700 1.15rem var(--mono)}
.runbar b.low{color:var(--red)}
.runbar span{color:var(--muted);flex:1}
[data-run] .quiz{max-width:860px}
.quiz.ok{border-left:4px solid var(--brand)}.quiz.bad{border-left:4px solid var(--red)}.quiz.skip{border-left:4px solid var(--line-2)}
.result{padding:26px;margin-bottom:16px;border-radius:18px;background:var(--surface);border:1px solid var(--line)}
.result h2{font-size:2.4rem;margin:0;letter-spacing:-.02em}
.weak{margin:4px 0 10px;padding-left:20px}


/* exam setup + analytics */
:root{--chart:#0b7a55;--good:#0b7a55;--warn:#b86e00;--bad:#d6404e}
[data-theme=dark]{--chart:#2aa87a;--good:#4ccf9c;--warn:#f0b14a;--bad:#ff7a85}
.modes-grid{grid-column:1/-1;display:grid;grid-template-columns:repeat(auto-fill,minmax(190px,1fr));gap:10px;border:0;padding:0;margin:0}
.modes-grid legend{padding:0;margin:0 0 8px}
.mode{position:relative;display:flex;flex-direction:column;gap:2px;padding:12px 14px;border:1px solid var(--line-2);border-radius:12px;cursor:pointer;color:var(--ink)}
.mode input{position:absolute;opacity:0}
.mode b{font-size:.95rem}
.mode small{font-weight:400;color:var(--muted);line-height:1.4}
.mode:has(input:checked){border-color:var(--brand);background:var(--brand-soft);box-shadow:inset 0 0 0 1px var(--brand)}
.subjects{grid-column:1/-1;display:flex;flex-wrap:wrap;gap:8px;border:0;padding:0;margin:0}
.subjects legend{padding:0;margin:0 0 8px}
.subj{position:relative;cursor:pointer}
.subj input{position:absolute;opacity:0}
.subj span{display:block;padding:6px 12px;border:1px solid var(--line-2);border-radius:999px;font-size:.9rem;color:var(--ink)}
.subj input:checked+span{border-color:var(--brand);background:var(--brand-soft);box-shadow:inset 0 0 0 1px var(--brand)}
.subj input:focus-visible+span{outline:2px solid var(--brand);outline-offset:2px}
.mode:has(input:focus-visible){outline:2px solid var(--brand);outline-offset:2px}
.dash{margin-top:8px}
.tiles{display:grid;grid-template-columns:repeat(auto-fill,minmax(150px,1fr));gap:12px}
.tile{padding:14px 16px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line)}
.tile small{display:block;color:var(--muted);font-size:.8rem;font-weight:600}
.tile b{font-size:1.6rem;letter-spacing:-.02em;font-variant-numeric:tabular-nums}
.recs{margin:14px 0;padding:14px 18px;border-radius:var(--radius);background:var(--brand-soft);color:var(--ink)}
.recs ul{margin:6px 0 0;padding-left:20px}
.panel{margin-top:14px;padding:18px 20px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line)}
.panel h3{margin:0 0 10px;font-size:1rem}
.panel .tw{margin:0;border:0;border-radius:0}
.chart{position:relative}
.chart svg{width:100%;height:auto;display:block;overflow:visible}
.chart .grid{stroke:var(--line);stroke-width:1}
.chart .ax,.chart .end{fill:var(--muted);font:500 11px var(--sans)}
.chart .end{fill:var(--ink);font-weight:700}
.chart .ln{fill:none;stroke:var(--chart);stroke-width:2;stroke-linejoin:round;stroke-linecap:round}
.chart .dot{fill:var(--chart);stroke:var(--surface);stroke-width:2}
.chart .hit{fill:transparent;cursor:pointer}
.chart .pt:hover .dot{r:6}
.chart .tip{position:absolute;transform:translate(-50%,-100%);background:var(--ink);color:var(--surface);font-size:.8rem;padding:4px 10px;border-radius:8px;white-space:nowrap;pointer-events:none}
.accbar{display:inline-block;width:80px;height:8px;border-radius:99px;background:var(--sunk);vertical-align:middle;overflow:hidden}
.accbar i{display:block;height:100%;background:var(--chart);border-radius:0 4px 4px 0}
.topics td{vertical-align:middle;font-variant-numeric:tabular-nums}
.st{font-size:.82rem;font-weight:600;white-space:nowrap}
.st.good{color:var(--good)}.st.ok{color:var(--warn)}.st.weak{color:var(--bad)}.st.fresh{color:var(--muted)}
.chip{background:none;cursor:pointer}
.tag{font-size:.75rem;color:var(--muted);border:1px solid var(--line);border-radius:999px;padding:0 8px;margin-left:6px;white-space:nowrap}
.btn.danger{color:var(--bad)}
.backup .btns{margin-top:6px}

/* papers page */
.papers{display:grid;gap:12px}
.paper{display:flex;gap:16px;padding:18px 20px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line)}
.paper .code{flex:none;display:grid;place-items:center;width:44px;height:44px;border-radius:12px;background:var(--brand-soft);color:var(--brand-ink);font-weight:800;font-size:1.2rem}
.paper h3{margin:0;font-size:1.05rem;line-height:1.4}
.paper .meta{margin:4px 0 8px}
.plinks{display:flex;flex-wrap:wrap;gap:8px;margin:0}
.chip{font-size:.82rem;font-weight:600;text-decoration:none;border:1px solid var(--line-2);border-radius:999px;padding:3px 12px;color:var(--ink)}
.chip:hover{border-color:var(--brand);color:var(--brand-ink)}
.prose.wide{max-width:none}

@media (max-width:1240px){.layout{grid-template-columns:260px minmax(0,1fr)}.toc-side{display:none}}
@media (max-width:920px){
  .layout{display:block}
  .menu{display:grid}
  .side{position:fixed;z-index:30;top:var(--top);left:0;width:min(320px,86vw);background:var(--surface);transform:translateX(-100%);
    transition:transform .2s;box-shadow:0 10px 40px rgba(0,0,0,.25)}
  .side.open{transform:none}
  .main{padding:20px 16px 0}
  .crumb{display:none}
  .links{display:none}
  .quick{display:block}
  .how{grid-template-columns:1fr}
}
@media (max-width:600px){
  .top{gap:6px;padding:0 12px}
  .icon{width:34px;height:34px}
  .brand{font-size:1rem}
  .ch-head h1{font-size:1.65rem}
  .prose h2{font-size:1.28rem}
  .two,.quiz .opts,.pn{grid-template-columns:1fr}
  .pn .next{grid-column:auto}
  .home-hero{padding:44px 0 26px}
  .home-hero h1{font-size:2.1rem}
  .course-hero{padding:22px}
  .course-hero h1{font-size:1.7rem}
  .box,.quiz{padding:12px 14px}
  .modes-grid{grid-template-columns:1fr 1fr}
  .mode small{display:none}
  .mode:has(input:checked) small{display:block}
}
/* bookmarks + notes */
.markbar{display:flex;gap:6px;align-items:center;margin-top:8px}
.star{background:none;border:0;cursor:pointer;font-size:1.15rem;line-height:1;color:var(--muted);padding:2px 4px;border-radius:6px}
.star.on{color:var(--warn)}
.star:hover,.note-btn:hover{color:var(--brand-ink)}
.note-btn{background:none;border:0;cursor:pointer;color:var(--muted);font:inherit;font-size:.85rem;padding:2px 4px}
textarea.note{display:block;width:100%;box-sizing:border-box;margin-top:6px;padding:8px 10px;border:1px solid var(--line-2);border-radius:10px;background:var(--bg);color:var(--ink);font:inherit;font-size:.92rem;resize:vertical}
h2 .markbar{display:inline-flex;margin:0 0 0 4px;vertical-align:.1em}
.marks ul{list-style:none;padding:0;margin:6px 0 14px}
.marks li{display:flex;gap:10px;align-items:baseline;flex-wrap:wrap;padding:9px 0;border-top:1px solid var(--line)}
.marks li a{flex:1 1 280px;color:var(--ink)}
.mnote{order:3;flex-basis:100%;margin:0;color:var(--muted);font-size:.9rem;white-space:pre-wrap}
.marks-h{display:flex;gap:10px;align-items:center;margin-top:6px}
/* exam review */
.src-line{display:block;margin-top:6px}
.filters{display:flex;gap:8px;flex-wrap:wrap}
.chip.on{border-color:var(--brand);background:var(--brand-soft);color:var(--brand-ink)}
.chip:disabled{opacity:.45;cursor:default}
[data-run][data-filter] .quiz{display:none}
[data-run][data-filter=bad] .quiz.bad,[data-run][data-filter=skip] .quiz.skip,[data-run][data-filter=ok] .quiz.ok{display:block}
/* daily goal + streak */
.meter{display:block;height:8px;border-radius:99px;background:var(--line);overflow:hidden;margin:8px 0}
.meter i{display:block;height:100%;background:var(--brand);border-radius:99px}
.daily-top{display:grid;grid-template-columns:minmax(0,2fr) auto auto minmax(0,1.3fr);gap:24px;align-items:center}
.daily-top>div>small{display:block;color:var(--muted);font-size:.8rem;font-weight:600}
.daily-top>div>b{font-size:1.6rem;font-variant-numeric:tabular-nums}
.daily .big{margin:0;font-size:1.05rem}.daily .big b{font-size:1.6rem}
.daily .meta{margin:0}
.daily-act{display:flex;flex-direction:column;gap:8px;align-items:flex-start}
.daily-act label{font-size:.85rem;color:var(--muted)}
.days{display:grid;grid-template-columns:repeat(28,1fr);gap:3px;margin-top:16px}
.days i,.legend i{display:block;aspect-ratio:1;border-radius:3px;background:var(--line)}
.days .some,.legend .some{background:color-mix(in srgb,var(--brand) 38%,var(--surface))}
.days .met,.legend .met{background:var(--brand)}
.legend{margin-top:8px!important}.legend i{display:inline-block;width:10px;height:10px;vertical-align:-1px;margin-left:8px}
.today{margin-top:10px!important;color:var(--ink)!important;font-size:.92rem}
.today .meter{display:inline-block;width:72px;vertical-align:middle;margin:0 6px 0 0}
@media (max-width:600px){
  .daily-top{grid-template-columns:1fr 1fr;gap:14px}
  .daily-top>div:first-child,.daily-act{grid-column:1/-1}
  .daily-act{flex-direction:row;align-items:center;flex-wrap:wrap}
  .days{grid-template-columns:repeat(14,1fr)}
}
.runbar small{color:var(--muted);font-weight:600;max-width:34%;overflow:hidden;text-overflow:ellipsis;white-space:nowrap}

@media (max-width:600px){.runbar small{display:none}}
/* accessibility */
.skip{position:absolute;left:12px;top:-60px;z-index:50;padding:8px 14px;border-radius:10px;background:var(--brand);color:#fff;font-weight:700;text-decoration:none}
.skip:focus{top:10px}
:focus-visible{outline:2px solid var(--brand);outline-offset:2px}
@media (prefers-reduced-motion:reduce){*,*::before,*::after{scroll-behavior:auto!important;transition:none!important;animation:none!important}}
.opt{min-height:44px}
p.sect{margin:-8px 0 14px}
/* tables: keep columns readable and scroll sideways, with a shadow hinting there is more */
.tw{background:linear-gradient(to right,var(--surface) 30%,transparent) left/40px 100% no-repeat local,
  linear-gradient(to left,var(--surface) 30%,transparent) right/40px 100% no-repeat local,
  radial-gradient(farthest-side at 0 50%,rgba(0,0,0,.2),transparent) left/14px 100% no-repeat scroll,
  radial-gradient(farthest-side at 100% 50%,rgba(0,0,0,.2),transparent) right/14px 100% no-repeat scroll,var(--surface)}
/* bottom tab bar (phones) */
.tabbar{display:none}
@media (max-width:760px){
  .tabbar{position:fixed;z-index:25;left:0;right:0;bottom:0;display:grid;grid-template-columns:repeat(5,1fr);
    padding:6px 4px calc(6px + env(safe-area-inset-bottom));background:color-mix(in srgb,var(--surface) 92%,transparent);
    backdrop-filter:blur(10px);border-top:1px solid var(--line)}
  .tabbar a{display:flex;flex-direction:column;align-items:center;gap:2px;padding:4px 0;border-radius:10px;text-decoration:none;
    color:var(--muted);font-size:.72rem;font-weight:600}
  .tabbar svg{width:22px;height:22px;fill:none;stroke:currentColor;stroke-width:1.8;stroke-linecap:round;stroke-linejoin:round}
  .tabbar a[aria-current]{color:var(--brand-ink)}
  .tabbar a[aria-current] svg{stroke-width:2.3}
  body{padding-bottom:calc(64px + env(safe-area-inset-bottom))}
}
@media (max-width:600px){
  .tw th,.tw td{min-width:9em}
  .practice .home-hero{padding:28px 0 18px}
  .practice .home-hero .lede{font-size:1rem}
}
/* exam question palette */
.palette{position:absolute;top:calc(100% + 6px);left:0;right:0;padding:14px;border-radius:var(--radius);background:var(--surface);
  border:1px solid var(--line-2);box-shadow:0 12px 40px rgba(0,0,0,.25)}
.pal-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(42px,1fr));gap:6px;max-height:46vh;overflow-y:auto}
.pal-grid button{height:40px;border-radius:9px;border:1px solid var(--line-2);background:var(--bg);color:var(--ink);font:600 .88rem var(--mono);cursor:pointer}
.pal-grid button.ans,.lg.ans{background:var(--brand-soft);border-color:var(--brand);color:var(--brand-ink)}
.pal-grid button.flag,.lg.flag{box-shadow:inset 0 -3px 0 var(--warn)}
.palette .meta{margin:10px 0 8px;font-size:.8rem}
.lg{display:inline-block;width:12px;height:12px;border-radius:3px;border:1px solid var(--line-2);vertical-align:-1px;margin-left:8px}
.lg:first-child{margin-left:0}
@media (max-width:600px){.runbar{gap:8px;padding:8px 10px}.runbar .btn{padding:8px 12px;font-size:.85rem}}
@media (max-width:920px){.side{padding-bottom:90px}}
.runbar .btn{white-space:nowrap}
.runbar small.wd{font:inherit;color:inherit}
@media (max-width:600px){.runbar small.wd{display:none}.runbar b{font-size:1rem}}
/* flashcards */
.fcard{max-width:760px;margin:0 auto;padding:28px 26px;border-radius:18px;background:var(--surface);border:1px solid var(--line);box-shadow:var(--shadow)}
.fcard .ctx{margin:0 0 6px;color:var(--muted);font-size:.85rem;font-weight:600}
.fcard .front{margin:0 0 18px;font-size:1.6rem;letter-spacing:-.01em;line-height:1.3}
.fcard .back{padding-top:16px;border-top:1px solid var(--line);line-height:1.65}
.fcard .back sub,.fcard .back sup{line-height:0}
.fc-acts{margin-top:18px}
.fc-acts .btn{display:inline-flex;align-items:center;gap:8px}
.fc-acts small{font-weight:500;opacity:.8}
.fc-acts kbd,.btn kbd{font:600 .7rem var(--mono);padding:1px 5px;border-radius:5px;border:1px solid currentColor;opacity:.6}
.cards-page [data-review] .runbar{max-width:760px;margin:0 auto 12px}
/* exam tracker + home countdown */
.countdown{display:flex;align-items:center;gap:14px;flex-wrap:wrap;padding:14px 18px;margin-bottom:16px;border-radius:var(--radius);background:var(--surface);border:1px solid var(--line)}
.countdown .dleft,.myexams .dleft{display:grid;place-items:center;min-width:52px;height:52px;padding:0 8px;border-radius:12px;background:var(--brand-soft);color:var(--brand-ink);font:800 1.4rem var(--mono)}
.countdown span{flex:1;min-width:200px}
.countdown a{font-weight:700;color:var(--brand-ink)}
.myexams{list-style:none;margin:0 0 14px;padding:0}
.myexams li{display:flex;align-items:center;gap:14px;padding:10px 0;border-top:1px solid var(--line)}
.myexams li div{flex:1}.myexams small{display:block;color:var(--muted)}
.myexams li.soon .dleft{background:color-mix(in srgb,var(--warn) 22%,var(--surface));color:var(--ink)}
.myexams li.past{opacity:.55}
.addexam{display:flex;gap:12px;flex-wrap:wrap;align-items:flex-end}
.addexam label{display:flex;flex-direction:column;gap:4px;font-size:.85rem;color:var(--muted);font-weight:600}
.addexam input{font:inherit;padding:9px 12px;border-radius:10px;border:1px solid var(--line-2);background:var(--bg);color:var(--ink);min-width:220px}
.official{margin:0 0 10px;padding-left:20px}
@media (max-width:600px){.fcard{padding:20px 16px}.fcard .front{font-size:1.3rem}.addexam input{min-width:0;width:100%}.addexam label{flex:1 1 100%}}
.exams .chip{white-space:nowrap;display:inline-block;margin:2px 0}