:root{--bg:#f5f6fa;--card:#fff;--ink:#1b1f2a;--mute:#6b7280;--line:#e3e6ee;--brand:#1f4fd8;--brand-ink:#fff;--ok:#16a34a;--warn:#d97706;--chip:#eef1fb;--shadow:0 1px 3px rgba(20,30,60,.08)}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]){--bg:#10131a;--card:#181c26;--ink:#e8ebf3;--mute:#9aa3b5;--line:#2a3040;--brand:#6b8cff;--brand-ink:#0b1020;--chip:#222a3d;--shadow:none}}
*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}
body{margin:0;background:var(--bg);color:var(--ink);font:16px/1.45 system-ui,-apple-system,"Segoe UI",Roboto,sans-serif}
a{color:var(--brand)}button{font:inherit;cursor:pointer}
.wrap{max-width:1000px;margin:0 auto;padding:0 16px}
header.top{position:sticky;top:0;z-index:5;background:var(--card);border-bottom:1px solid var(--line)}
header.top .wrap{display:flex;align-items:center;gap:12px;height:54px}
.logo{font-weight:700;letter-spacing:.3px}.logo b{color:var(--brand)}
nav.tabs{display:flex;gap:4px;margin-left:8px;overflow-x:auto}
nav.tabs a{padding:8px 12px;border-radius:8px;text-decoration:none;color:var(--mute);white-space:nowrap}
nav.tabs a.on{background:var(--chip);color:var(--brand);font-weight:600}
.sp{flex:1}.who{color:var(--mute);font-size:14px;white-space:nowrap}
.btn{border:1px solid var(--line);background:var(--card);color:var(--ink);padding:8px 14px;border-radius:10px}
.btn.pri{background:var(--brand);color:var(--brand-ink);border-color:var(--brand)}
.btn.sm{padding:5px 10px;font-size:14px}
main{padding:16px 0 80px}
h1{font-size:22px;margin:8px 0 12px}h2{font-size:18px;margin:22px 0 8px}
.card{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:14px;box-shadow:var(--shadow)}
.filters{display:grid;gap:10px;margin-bottom:14px}
.row{display:flex;flex-wrap:wrap;gap:6px;align-items:center}
.lbl{font-size:12px;color:var(--mute);text-transform:uppercase;letter-spacing:.5px;margin-right:4px;min-width:64px}
.chip{border:1px solid var(--line);background:var(--card);color:var(--ink);padding:5px 11px;border-radius:999px;font-size:14px}
.chip.on{background:var(--brand);color:var(--brand-ink);border-color:var(--brand)}
.chip.num{min-width:36px;text-align:center;padding:5px 8px}
input[type=search],input[type=text],input[type=password],select{width:100%;padding:10px 12px;border:1px solid var(--line);border-radius:10px;background:var(--card);color:var(--ink);font:inherit}
.count{color:var(--mute);font-size:14px;margin:4px 0 10px}
.mod{margin:18px 0 6px;font-weight:700;display:flex;gap:8px;align-items:baseline}
.mod small{color:var(--mute);font-weight:400}
.lesson{display:flex;gap:12px;align-items:flex-start;text-decoration:none;color:inherit;margin-bottom:8px}
.lesson .num{flex:0 0 34px;height:34px;border-radius:9px;background:var(--chip);color:var(--brand);display:grid;place-items:center;font-weight:700}
.lesson .body{flex:1;min-width:0}.lesson .ttl{font-weight:600}
.meta{display:flex;flex-wrap:wrap;gap:6px;margin-top:6px;font-size:13px;color:var(--mute);align-items:center}
.tag{background:var(--chip);border-radius:6px;padding:2px 7px;font-size:12px;color:var(--ink)}
.tag.task{background:#fff3d6;color:#7a4b00}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]) .tag.task{background:#3a2f12;color:#f4c46a}}
.st{flex:0 0 auto;font-size:13px;white-space:nowrap}.st.done{color:var(--ok)}.st.part{color:var(--warn)}
.video{aspect-ratio:16/9;width:100%;background:#0d1020;border-radius:14px;display:grid;place-items:center;color:#cbd2ea;text-align:center;overflow:hidden}
.video video{width:100%;height:100%;background:#000}
.video .ph{padding:20px}.video .ph b{display:block;font-size:18px;margin-bottom:6px}
.files{display:grid;gap:8px}
.file{display:flex;gap:10px;align-items:center;justify-content:space-between}
.file .nm{min-width:0;overflow-wrap:anywhere;cursor:pointer}.file .nm:hover>div:first-child{text-decoration:underline}.file .k{color:var(--mute);font-size:13px}
.grid3{display:grid;grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:10px}
.stat{text-align:center}.stat .v{font-size:28px;font-weight:700;color:var(--brand)}.stat .l{color:var(--mute);font-size:13px}
.bar{height:8px;background:var(--chip);border-radius:6px;overflow:hidden}.bar i{display:block;height:100%;background:var(--brand)}
table{width:100%;border-collapse:collapse;font-size:14px}th,td{text-align:left;padding:8px 6px;border-bottom:1px solid var(--line);vertical-align:top}th{color:var(--mute);font-weight:600}
.login{max-width:380px;margin:12vh auto 0;display:grid;gap:12px}
.err{color:#dc2626;font-size:14px}.hint{color:var(--mute);font-size:13px}
.viewer{position:fixed;inset:0;background:var(--bg);z-index:20;display:flex;flex-direction:column}
.viewer .bar2{display:flex;gap:8px;align-items:center;padding:8px 12px;border-bottom:1px solid var(--line);background:var(--card)}
.viewer .bar2 .t{flex:1;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.viewer iframe{flex:1;border:0;width:100%}
.pdfbox{flex:1;overflow:auto;-webkit-overflow-scrolling:touch;background:#8a8f98;padding:8px;text-align:center}
.pdfbox .pg{margin:0 auto 8px;background:#fff;width:fit-content;max-width:100%}
.pdfbox canvas{display:block}
.pdfbox .empty{color:#fff}
.viewer .empty{flex:1;display:grid;place-items:center;text-align:center;padding:24px;color:var(--mute)}
.demo{background:#fff3d6;color:#7a4b00;font-size:13px;text-align:center;padding:4px}
.crumb{font-size:14px;margin:4px 0 8px}

.chapters{margin:12px 0}.chapters h2{margin:0 0 6px}.chap{display:block;width:100%;text-align:left;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:9px 12px;margin:4px 0;font:inherit;color:inherit;cursor:pointer}.chap .tm{display:inline-block;min-width:3.2em;color:var(--mute);font-variant-numeric:tabular-nums}.chap.on{border-color:var(--pri,#1f4fd8);background:rgba(31,79,216,.08)}

.gbar{margin:10px 0 14px}.gtop{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;text-align:center}
.gs b{display:block;font-size:20px}.gs span{font-size:12px;color:var(--mute)}
.gtask{margin-top:12px}.gl{font-weight:600;margin-bottom:6px}
.gbarline{height:10px;border-radius:6px;background:var(--line);overflow:hidden;margin-bottom:8px}.gbarline i{display:block;height:100%;background:#2e9e5b;border-radius:6px}
.gbarline.thin{height:6px;margin:4px 0 0}.gbarline.thin i{background:var(--pri,#1f4fd8)}
.glv{margin-top:8px;font-size:12px;color:var(--mute)}
.cal{display:grid;grid-template-columns:repeat(7,1fr);gap:6px}
.cd{aspect-ratio:1;display:grid;place-items:center;border-radius:8px;border:1px solid var(--line);font-size:13px;color:var(--mute)}
.cd.strike{background:#2e9e5b;color:#fff;border-color:#2e9e5b}.cd.frozen{background:#7cc4f0;color:#06324f;border-color:#7cc4f0}.cd.today{border-color:var(--pri,#1f4fd8);color:inherit;font-weight:700}
.badge{display:inline-block;margin:3px 6px 3px 0;padding:5px 10px;border-radius:14px;background:rgba(46,158,91,.14);font-size:13px}
.btn[disabled]{opacity:.45;cursor:default}

.chap-part{margin:14px 0 4px;font-weight:600;color:var(--mute);font-size:.95em;text-transform:none;letter-spacing:.01em}.chap-kind{float:right;font-size:.75em;padding:1px 7px;border-radius:9px;background:var(--line);color:var(--mute);margin-left:8px}.chap-kind.k-практика{background:rgba(31,160,90,.15);color:#1a8a4e}.chap-kind.k-итог{background:rgba(214,140,20,.15);color:#a8680c}.chap-kind.k-разбор{background:rgba(31,79,216,.12);color:#1f4fd8}

.sbox{margin:12px 0;padding:10px 12px;border:1px solid var(--line,#ddd);border-radius:12px}
.sbox h2{margin:0 0 6px;font-size:1rem}
.shit{margin:8px 0;padding-top:6px;border-top:1px solid var(--line,#eee)}
.stitle{font-weight:600}
.sline{display:block;padding:4px 0;text-decoration:none;color:inherit;font-size:.92rem}
.sline .tm{display:inline-block;min-width:44px;font-weight:600;color:var(--accent,#2a6)}
.sline mark{background:#ffe27a;color:inherit;border-radius:3px;padding:0 1px}

.task{margin:10px 0}
.tmeta{font-size:.8rem;color:var(--muted,#666);margin-bottom:6px}
.ttext{margin:6px 0;line-height:1.45}
.timg{display:block;max-width:100%;height:auto;margin:8px 0;background:#fff;border-radius:8px}
.tok{color:#1a7f37;font-weight:600}
.tres{margin-top:6px}
.tmore{margin:8px 0}

.task.with-help{display:grid;grid-template-columns:1fr;gap:10px}
.thelp{border:1px solid var(--line,#ddd);border-radius:12px;padding:10px;background:rgba(127,127,127,.06)}
.thead{font-weight:600;display:flex;justify-content:space-between;align-items:center;margin-bottom:6px}
.tchat{max-height:260px;overflow:auto;display:flex;flex-direction:column;gap:6px;margin-bottom:8px}
.tb{padding:6px 10px;border-radius:12px;max-width:92%;line-height:1.4;font-size:.92rem}
.tb.me{align-self:flex-end;background:#d7ecff;color:#123}
.tb.bot{align-self:flex-start;background:#eee;color:#222}
@media(min-width:900px){.task.with-help{grid-template-columns:minmax(0,1.4fr) minmax(280px,1fr)}.task.with-help>.tmeta,.task.with-help>.ttext,.task.with-help>.timg,.task.with-help>.row,.task.with-help>.tres{grid-column:1}.task.with-help>.thelp{grid-column:2;grid-row:1 / span 6}}

.twait{display:flex;gap:10px;align-items:center;padding:10px;border-radius:12px;background:rgba(80,160,255,.12);line-height:1.35;font-size:.92rem}
.tico{font-size:2rem;animation:tbob 1.2s ease-in-out infinite}
.tsec{margin-top:4px;color:var(--muted,#667);font-size:.85rem}
@keyframes tbob{0%,100%{transform:translateY(0)}50%{transform:translateY(-5px)}}