/* ===== «Седьмой Класс за Минуту» — дизайн-система =====
   Белый, строгий, спокойный. Один акцентный цвет. */

@font-face{
  font-family:"Hirro Sans";
  src:url("../fonts/hirro-sans.ttf") format("truetype");
  font-weight:400;
  font-style:normal;
  font-display:swap;
}

:root{
  --bg:#ffffff;
  --surface:#ffffff;
  --surface-2:#fafafa;
  --ink:#1f2328;
  --ink-2:#3d444d;
  --muted:#6b7280;
  --muted-2:#8b939e;
  --line:#e5e7eb;
  --line-2:#eef0f3;
  --accent:#2563eb;
  --accent-ink:#1d4ed8;
  --accent-soft:#eff4ff;
  --ok:#15803d;
  --ok-soft:#eefbf1;
  --bad:#b91c1c;
  --bad-soft:#fdf0f0;
  --warn:#a16207;
  --radius:10px;
  --radius-sm:7px;
  --shadow:0 1px 2px rgba(16,24,40,.04), 0 8px 24px -12px rgba(16,24,40,.12);
  --maxw:820px;
  --mono:ui-monospace,"SF Mono",Menlo,Consolas,"Liberation Mono",monospace;
  --sans:"Hirro Sans",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,"Helvetica Neue",Arial,sans-serif;
}

*{box-sizing:border-box}
html{-webkit-text-size-adjust:100%}
body{
  margin:0;background:var(--bg);color:var(--ink);font-family:var(--sans);
  font-size:16px;line-height:1.62;-webkit-font-smoothing:antialiased;
}
a{color:var(--accent-ink);text-decoration:none}
a:hover{text-decoration:underline}
h1,h2,h3,h4{line-height:1.28;margin:0;font-weight:650;letter-spacing:-.01em}
p{margin:0 0 .85em}
ul,ol{margin:0 0 .85em;padding-left:1.35em}
li{margin:.25em 0}
code{font-family:var(--mono);font-size:.92em;background:var(--surface-2);border:1px solid var(--line-2);border-radius:5px;padding:.08em .38em}
hr{border:0;border-top:1px solid var(--line);margin:1.6em 0}

/* ---------- верхняя панель ---------- */
.topbar{position:sticky;top:0;z-index:40;background:rgba(255,255,255,.92);backdrop-filter:blur(8px);border-bottom:1px solid var(--line)}
.topbar-inner{max-width:1280px;margin:0 auto;display:flex;align-items:center;gap:14px;padding:10px 18px}
.burger{display:none;width:38px;height:38px;border:1px solid var(--line);background:#fff;border-radius:var(--radius-sm);cursor:pointer;padding:0;flex:none}
.burger span{display:block;width:16px;height:1.6px;background:var(--ink);margin:3.2px auto;border-radius:2px}
.brand{display:flex;align-items:center;gap:10px;color:var(--ink);flex:none}
.brand:hover{text-decoration:none}
.brand-mark{width:32px;height:32px;border-radius:8px;background:var(--accent);color:#fff;display:grid;place-items:center;font-weight:700;font-size:17px}
.brand-text{display:flex;flex-direction:column;line-height:1.15}
.brand-text strong{font-size:15px}
.brand-text em{font-style:normal;font-size:11.5px;color:var(--muted)}
.search-wrap{position:relative;flex:1;max-width:440px;margin-left:auto}
#search{width:100%;height:38px;border:1px solid var(--line);border-radius:var(--radius-sm);padding:0 34px 0 12px;font:inherit;font-size:14.5px;background:#fff;color:var(--ink)}
#search:focus{outline:none;border-color:var(--accent);box-shadow:0 0 0 3px var(--accent-soft)}
.search-clear{position:absolute;right:6px;top:50%;transform:translateY(-50%);border:0;background:transparent;font-size:20px;line-height:1;color:var(--muted);cursor:pointer;padding:4px 7px;border-radius:5px}
.search-results{position:absolute;top:44px;left:0;right:0;background:#fff;border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);max-height:60vh;overflow:auto;padding:5px}
.sr-item{display:block;padding:8px 10px;border-radius:var(--radius-sm);color:var(--ink)}
.sr-item:hover,.sr-item:focus{background:var(--accent-soft);text-decoration:none}
.sr-item b{font-weight:600}
.sr-item small{display:block;color:var(--muted);font-size:12.5px;margin-top:1px}
.sr-empty{padding:12px;color:var(--muted);font-size:14px}
.topbar-progress{display:flex;align-items:center;gap:8px;flex:none;font-size:12.5px;color:var(--muted)}
.topbar-progress .bar{width:74px;height:5px;border-radius:99px;background:var(--line);overflow:hidden;display:block}
.topbar-progress .bar i{display:block;height:100%;width:0;background:var(--accent);transition:width .25s}

/* ---------- каркас ---------- */
.shell{max-width:1280px;margin:0 auto;display:grid;grid-template-columns:298px minmax(0,1fr);gap:0;align-items:start}
.sidebar{position:sticky;top:59px;max-height:calc(100vh - 59px);overflow-y:auto;border-right:1px solid var(--line);padding:18px 12px 28px 18px}
.toc{font-size:14.2px}
.toc-ch{margin-bottom:14px}
.toc-ch-title{display:flex;gap:8px;align-items:baseline;font-weight:650;font-size:13.2px;color:var(--ink-2);padding:6px 8px 4px;line-height:1.35}
.toc-ch-title .tag{color:var(--muted-2);font-weight:600;font-size:11.4px;text-transform:uppercase;letter-spacing:.05em;flex:none}
.toc-list{list-style:none;margin:0;padding:0}
.toc-list a{display:flex;gap:8px;align-items:baseline;padding:5px 8px;border-radius:var(--radius-sm);color:var(--ink-2)}
.toc-list a:hover{background:var(--surface-2);text-decoration:none}
.toc-list a.active{background:var(--accent-soft);color:var(--accent-ink);font-weight:600}
.toc-list a.done .toc-num{color:var(--ok);border-color:#cfe9d6;background:var(--ok-soft)}
.toc-num{flex:none;width:30px;font-size:12.5px;color:var(--muted);font-variant-numeric:tabular-nums;border:1px solid var(--line);border-radius:5px;text-align:center;line-height:1.5}
.sidebar-foot{margin-top:20px;padding-top:14px;border-top:1px solid var(--line-2)}
.sidebar-note{font-size:11.6px;color:var(--muted-2);margin:10px 0 0;line-height:1.5}

.content{padding:30px 30px 90px;min-width:0}
.wrap{max-width:var(--maxw);margin:0 auto}

/* ---------- главная ---------- */
.hero{padding:10px 0 26px;border-bottom:1px solid var(--line);margin-bottom:26px}
.hero h1{font-size:31px;margin-bottom:10px}
.hero .lead{font-size:16.6px;color:var(--ink-2);max-width:62ch}
.hero .meta{margin-top:14px;font-size:13px;color:var(--muted);display:flex;flex-wrap:wrap;gap:6px 16px}
.stats{display:grid;grid-template-columns:repeat(auto-fit,minmax(148px,1fr));gap:12px;margin:22px 0 30px}
.stat{border:1px solid var(--line);border-radius:var(--radius);padding:13px 15px;background:var(--surface)}
.stat b{display:block;font-size:23px;font-weight:650;letter-spacing:-.02em}
.stat span{font-size:12.6px;color:var(--muted)}
.howto{border:1px solid var(--line);border-radius:var(--radius);background:var(--surface-2);padding:16px 18px;margin-bottom:30px}
.howto h3{font-size:14px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin-bottom:10px}
.howto ol{margin:0;padding-left:1.2em;font-size:14.6px}

.chapter-card{border:1px solid var(--line);border-radius:var(--radius);padding:0;margin-bottom:14px;overflow:hidden;background:var(--surface)}
.chapter-head{display:flex;gap:12px;align-items:center;padding:14px 16px;border-bottom:1px solid var(--line-2);background:var(--surface-2)}
.chapter-head .ch-tag{flex:none;font-size:11.5px;font-weight:700;letter-spacing:.05em;text-transform:uppercase;color:var(--accent-ink);background:var(--accent-soft);border-radius:6px;padding:4px 8px}
.chapter-head h3{font-size:16.5px;margin:0}
.chapter-head .ch-count{margin-left:auto;font-size:12.5px;color:var(--muted);white-space:nowrap}
.chapter-body{padding:8px 10px 10px}
.chapter-body .toc-list a{padding:6px 8px}

/* ---------- параграф ---------- */
.p-head{margin-bottom:22px}
.crumbs{font-size:12.6px;color:var(--muted);margin-bottom:10px}
.crumbs a{color:var(--muted)}
.p-head h1{font-size:27px;margin-bottom:8px}
.p-head h1 .p-num{color:var(--accent);font-variant-numeric:tabular-nums}
.p-head .p-meta{font-size:13px;color:var(--muted);display:flex;flex-wrap:wrap;gap:4px 14px;align-items:center}
.p-head .p-src{border:1px solid var(--line);border-radius:6px;padding:2px 7px;font-size:12.3px}

.block{border:1px solid var(--line);border-radius:var(--radius);margin:0 0 22px;background:var(--surface);overflow:hidden}
.block-head{display:flex;align-items:center;gap:10px;padding:12px 16px;border-bottom:1px solid var(--line-2);background:var(--surface-2)}
.block-head h2{font-size:15px;margin:0;letter-spacing:.01em}
.block-head .idx{width:22px;height:22px;flex:none;border-radius:6px;background:var(--accent);color:#fff;font-size:12px;display:grid;place-items:center;font-weight:700}
.block-body{padding:16px}
.block-body>*:last-child{margin-bottom:0}

.brief p{font-size:16.2px}
.brief .kbd-list{margin:.2em 0 1em}

/* Обязательно выучить */
.must .def{border-left:3px solid var(--accent);background:var(--accent-soft);border-radius:0 var(--radius-sm) var(--radius-sm) 0;padding:10px 14px;margin:0 0 10px}
.must .def .term{font-weight:650}
.must .def .src{display:block;margin-top:5px;font-size:12.2px;color:var(--muted);font-style:normal}
.must .def .own{color:var(--muted);font-size:12.2px}
.must h4{font-size:12.8px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin:16px 0 8px}
.must h4:first-child{margin-top:0}
.must ul.plain{list-style:none;padding:0}
.must ul.plain li{position:relative;padding-left:18px}
.must ul.plain li::before{content:"";position:absolute;left:4px;top:.62em;width:5px;height:5px;border-radius:50%;background:var(--accent)}
.formula{border:1px solid var(--line);border-radius:var(--radius-sm);padding:12px 14px;margin:0 0 10px;background:var(--surface-2)}
.formula .expr{font-family:var(--mono);font-size:16px;text-align:center;padding:6px 0 10px;color:var(--ink);letter-spacing:.02em}
.formula .legend{display:grid;grid-template-columns:auto 1fr;gap:3px 12px;font-size:14.2px}
.formula .legend .sym{font-family:var(--mono);color:var(--accent-ink);font-weight:600}
.formula .legend .unit{color:var(--muted)}
.formula .example{margin-top:10px;padding-top:10px;border-top:1px dashed var(--line);font-size:14.2px;color:var(--ink-2)}
.formula .example b{color:var(--ink)}

/* Интерактив */
.lab .lab-body{padding:0}
.lab-stage{position:relative;background:#fcfcfd;border-bottom:1px solid var(--line-2)}
.lab-stage canvas{display:block;width:100%;height:auto;touch-action:none}
.lab-controls{display:grid;grid-template-columns:repeat(auto-fit,minmax(210px,1fr));gap:12px 18px;padding:14px 16px;border-bottom:1px solid var(--line-2)}
.ctrl{display:flex;flex-direction:column;gap:5px;min-width:0}
.ctrl label{font-size:13px;color:var(--ink-2);display:flex;justify-content:space-between;gap:8px;align-items:baseline}
.ctrl label .val{font-family:var(--mono);font-size:12.6px;color:var(--accent-ink);font-weight:600}
.ctrl input[type=range]{width:100%;accent-color:var(--accent);height:22px}
.ctrl select{height:34px;border:1px solid var(--line);border-radius:var(--radius-sm);padding:0 8px;font:inherit;font-size:14px;background:#fff;color:var(--ink)}
.ctrl .hintline{font-size:11.8px;color:var(--muted-2)}
.lab-actions{display:flex;flex-wrap:wrap;gap:8px;padding:12px 16px;border-bottom:1px solid var(--line-2);background:var(--surface-2)}
.lab-notes{display:grid;grid-template-columns:repeat(auto-fit,minmax(240px,1fr));gap:14px;padding:16px}
.note h5{font-size:12.4px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin:0 0 5px}
.note p{font-size:14.3px;margin:0;color:var(--ink-2)}
.readout{position:absolute;right:10px;top:10px;background:rgba(255,255,255,.94);border:1px solid var(--line);border-radius:var(--radius-sm);padding:8px 10px;font-size:12.6px;line-height:1.5;font-family:var(--mono);color:var(--ink-2);pointer-events:none;max-width:60%}
.readout b{color:var(--accent-ink);font-weight:600}
.badge-scale{position:absolute;right:10px;bottom:10px;background:rgba(255,255,255,.94);border:1px solid var(--line);border-radius:5px;padding:2px 7px;font-size:11.4px;color:var(--muted)}

/* Проверь себя */
.quiz-q{border-top:1px solid var(--line-2);padding:14px 0}
.quiz-q:first-child{border-top:0;padding-top:0}
.quiz-q .qtext{font-weight:600;margin-bottom:10px;display:flex;gap:9px}
.quiz-q .qtext .qn{flex:none;color:var(--accent);font-variant-numeric:tabular-nums}
.opts{display:flex;flex-direction:column;gap:6px;margin-bottom:10px}
.opt{display:flex;gap:9px;align-items:flex-start;border:1px solid var(--line);border-radius:var(--radius-sm);padding:8px 11px;cursor:pointer;font-size:14.6px;background:#fff;transition:border-color .12s,background .12s}
.opt:hover{border-color:#cdd5e0}
.opt input{margin:3px 0 0;accent-color:var(--accent);flex:none}
.opt.correct{border-color:#bfe3c8;background:var(--ok-soft)}
.opt.wrong{border-color:#f0c6c6;background:var(--bad-soft)}
.opt.chosen{font-weight:600}
.explain{font-size:14.2px;border-radius:var(--radius-sm);padding:9px 12px;margin-top:4px;display:none}
.explain.show{display:block}
.explain.ok{background:var(--ok-soft);color:#14532d;border:1px solid #cfe9d6}
.explain.no{background:var(--bad-soft);color:#7f1d1d;border:1px solid #f0c6c6}
.quiz-actions{display:flex;gap:10px;align-items:center;margin-top:14px;padding-top:14px;border-top:1px solid var(--line-2);flex-wrap:wrap}
.quiz-score{font-size:14.4px;font-weight:600;margin-left:auto}

/* кнопки */
.btn{display:inline-flex;align-items:center;gap:7px;border:1px solid var(--line);background:#fff;color:var(--ink);border-radius:var(--radius-sm);padding:8px 14px;font:inherit;font-size:14.2px;cursor:pointer;line-height:1.3}
.btn:hover{border-color:#cdd5e0;background:var(--surface-2)}
.btn-primary{background:var(--accent);border-color:var(--accent);color:#fff}
.btn-primary:hover{background:var(--accent-ink);border-color:var(--accent-ink)}
.btn-ghost{background:transparent;border-color:var(--line)}
.btn-block{width:100%;justify-content:center}
.btn:disabled{opacity:.5;cursor:not-allowed}
.btn-sm{padding:5px 10px;font-size:13px}

/* навигация по параграфам */
.pnav{display:flex;gap:10px;align-items:stretch;margin:26px 0 10px}
.pnav a{flex:1;border:1px solid var(--line);border-radius:var(--radius);padding:11px 14px;color:var(--ink);display:flex;flex-direction:column;gap:2px;min-width:0}
.pnav a:hover{text-decoration:none;border-color:#cdd5e0;background:var(--surface-2)}
.pnav a.next{text-align:right;align-items:flex-end}
.pnav a .lbl{font-size:11.8px;color:var(--muted);text-transform:uppercase;letter-spacing:.05em}
.pnav a .ttl{font-size:14.4px;font-weight:600;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;max-width:100%}
.pnav a.disabled{visibility:hidden}
.learn-bar{display:flex;align-items:center;gap:12px;border:1px solid var(--line);border-radius:var(--radius);padding:12px 14px;background:var(--surface-2);margin-bottom:8px;flex-wrap:wrap}
.learn-bar .state{font-size:14.4px;color:var(--ink-2)}
.learn-bar .state b{color:var(--ok)}

/* тест главы */
.test-intro{border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;background:var(--surface-2);margin-bottom:20px}
.scale-table{width:100%;border-collapse:collapse;font-size:14.3px;margin-top:10px}
.scale-table th,.scale-table td{border:1px solid var(--line);padding:7px 10px;text-align:left}
.scale-table th{background:#fff;font-weight:600;color:var(--ink-2)}
.test-result{border:1px solid var(--line);border-radius:var(--radius);padding:16px 18px;margin-bottom:20px;background:var(--surface)}
.test-result .big{font-size:30px;font-weight:700;letter-spacing:-.02em}
.test-result .grade{display:inline-grid;place-items:center;width:52px;height:52px;border-radius:12px;font-size:26px;font-weight:700;color:#fff;background:var(--accent)}
.test-result .row{display:flex;align-items:center;gap:16px;flex-wrap:wrap}
.review-link{font-size:13.6px}

.updated{font-size:12.6px;color:var(--muted);margin-top:8px}
.notice{border:1px solid #f0e2b8;background:#fffaf0;border-radius:var(--radius-sm);padding:11px 14px;font-size:13.8px;color:#6b4e12;margin-bottom:18px}
.notice b{color:#4a3708}

.page-foot{max-width:1280px;margin:0 auto;padding:16px 30px 30px;display:flex;justify-content:space-between;gap:12px;font-size:12.4px;color:var(--muted-2);border-top:1px solid var(--line-2)}

.scrim{position:fixed;inset:0;background:rgba(15,23,42,.35);z-index:45}

/* ---------- адаптив ---------- */
@media (max-width:1000px){
  .shell{grid-template-columns:1fr}
  .sidebar{position:fixed;top:0;left:0;bottom:0;width:298px;max-height:none;background:#fff;z-index:50;transform:translateX(-102%);transition:transform .22s ease;border-right:1px solid var(--line);padding-top:16px}
  .sidebar.open{transform:none}
  .burger{display:block}
  .topbar-progress .bar{display:none}
  .content{padding:20px 16px 80px}
  .hero h1{font-size:25px}
  .p-head h1{font-size:22px}
  .brand-text em{display:none}
}
@media (max-width:620px){
  .search-wrap{max-width:none}
  .topbar-inner{gap:9px;padding:9px 12px}
  .brand-text strong{font-size:14px}
  .pnav{flex-direction:column}
  .pnav a.next{text-align:left;align-items:flex-start}
  .lab-notes{grid-template-columns:1fr}
  .quiz-score{margin-left:0;width:100%}
  .page-foot{padding:14px 16px 26px;flex-direction:column;gap:4px}
}
@media print{.topbar,.sidebar,.scrim,.lab-actions,.pnav,.learn-bar{display:none}}

/* ============================================================
   Графическое оформление: иллюстрации, объёмные карточки
   ============================================================ */

/* ---------- иллюстрация к параграфу ---------- */
.p-figure{
  margin:0 0 26px;border:1px solid var(--line);border-radius:14px;overflow:hidden;
  background:var(--surface);box-shadow:0 1px 2px rgba(16,24,40,.04),0 14px 34px -20px rgba(16,24,40,.28);
}
.p-figure img{display:block;width:100%;height:auto;aspect-ratio:3/2;object-fit:cover;background:#eef3fa}
.p-figure figcaption{
  padding:9px 15px;font-size:12.8px;color:var(--muted);
  border-top:1px solid var(--line-2);background:var(--surface-2);
}
.p-figure figcaption b{color:var(--ink-2);font-weight:600}

/* несколько иллюстраций к параграфу — сеткой */
.p-figures{margin:0 0 26px}
.p-figures .p-figure{margin:0}
.p-figures.many{display:grid;grid-template-columns:repeat(auto-fit,minmax(238px,1fr));gap:12px}
.p-figures.many .p-figure img{aspect-ratio:4/3}
.p-figures.many .p-figure figcaption{font-size:12px;padding:7px 11px}

/* ---------- миниатюра главы на главной ---------- */
.chapter-thumb{
  display:block;width:100%;aspect-ratio:2.6/1;object-fit:cover;object-position:center 45%;
  background:linear-gradient(180deg,#eef3fa,#dfe8f4);border-bottom:1px solid var(--line-2);
}

/* ---------- галерея тем на главной ---------- */
.gallery{margin:0 0 30px}
.gallery h3{font-size:14px;text-transform:uppercase;letter-spacing:.05em;color:var(--muted);margin-bottom:12px}
.gallery-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(148px,1fr));gap:12px}
.gal-item{
  margin:0;border:1px solid var(--line);border-radius:12px;overflow:hidden;background:var(--surface);
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 12px 28px -22px rgba(16,24,40,.30);
}
.gal-item img{display:block;width:100%;aspect-ratio:16/9;object-fit:cover;background:#eef3fa}
.gal-item figcaption{padding:7px 10px;font-size:12.4px;color:var(--muted);border-top:1px solid var(--line-2);background:var(--surface-2)}

/* ---------- объёмные карточки ---------- */
.chapter-card{
  border-radius:14px;
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 12px 30px -22px rgba(16,24,40,.30);
  transition:box-shadow .18s ease,transform .18s ease;
}
.chapter-card:hover{box-shadow:0 2px 4px rgba(16,24,40,.05),0 20px 40px -22px rgba(16,24,40,.34);transform:translateY(-1px)}
.chapter-head{background:linear-gradient(180deg,#fbfcfe,#f4f7fb)}

.stat{
  border-radius:13px;background:linear-gradient(180deg,#ffffff,#f7fafd);
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 10px 26px -20px rgba(16,24,40,.30);
}
.stat b{background:linear-gradient(180deg,var(--ink),#3d444d);-webkit-background-clip:text;background-clip:text;color:transparent}

.hero{
  border-radius:16px;border:1px solid var(--line);border-bottom:1px solid var(--line);
  padding:26px 26px 24px;margin-bottom:26px;
  background:linear-gradient(135deg,#f7faff 0%,#ffffff 55%,#f4f8ff 100%);
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 18px 44px -30px rgba(16,24,40,.35);
}
.howto{border-radius:13px}

/* ---------- панель модели ---------- */
.lab-stage{
  border-radius:12px;overflow:hidden;
  box-shadow:0 1px 2px rgba(16,24,40,.05),0 12px 30px -24px rgba(16,24,40,.32);
}
.lab-actions .btn{box-shadow:0 1px 2px rgba(16,24,40,.05)}

/* ---------- плавность появления ---------- */
.p-figure,.chapter-card,.stat,.hero{animation:fadeUp .32s ease both}
@keyframes fadeUp{from{opacity:0;transform:translateY(6px)}to{opacity:1;transform:none}}
@media (prefers-reduced-motion:reduce){
  .p-figure,.chapter-card,.stat,.hero{animation:none}
  .chapter-card:hover{transform:none}
}

/* ============================================================
   Главная страница: выбор предмета
   ============================================================ */
.landing{padding:26px 0 4px;border-bottom:1px solid var(--line);margin-bottom:24px}
.landing h1{font-size:34px;margin-bottom:12px;letter-spacing:-.02em}
.landing .lead{font-size:17px;color:var(--ink-2);max-width:60ch;margin:0}
.landing .meta{margin-top:16px;font-size:13px;color:var(--muted);display:flex;flex-wrap:wrap;gap:6px 16px}

.subjects{display:grid;grid-template-columns:repeat(auto-fill,minmax(272px,1fr));gap:14px;margin:0 0 18px}
.subject-card{
  display:flex;align-items:center;gap:14px;padding:16px 18px;border:1px solid var(--line);
  border-radius:14px;background:linear-gradient(180deg,#fff,#f8fbfe);color:var(--ink);
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 12px 30px -22px rgba(16,24,40,.30);
  transition:box-shadow .18s ease,transform .18s ease,border-color .18s ease;
}
a.subject-card:hover{text-decoration:none;transform:translateY(-2px);border-color:#c9dcfb;
  box-shadow:0 2px 4px rgba(16,24,40,.05),0 20px 40px -22px rgba(16,24,40,.36)}
.s-mark{
  flex:none;width:46px;height:46px;border-radius:12px;display:grid;place-items:center;
  font-size:21px;font-weight:650;color:#fff;background:linear-gradient(160deg,#3b82f6,#1d4ed8);
  box-shadow:0 6px 14px -8px rgba(29,78,216,.85);
}
.s-body{display:flex;flex-direction:column;gap:2px;min-width:0}
.s-body strong{font-size:17px}
.s-body em{font-style:normal;font-size:12.8px;color:var(--muted)}
.s-go{margin-left:auto;font-size:13px;color:var(--accent-ink);white-space:nowrap;flex:none}
.subject-card.soon{background:var(--surface-2);box-shadow:none;border-style:dashed}
.subject-card.soon .s-mark{background:linear-gradient(160deg,#cfd8e3,#aab6c4);box-shadow:none}
.subject-card.soon .s-body strong{color:var(--muted)}
.subject-card.soon .s-go{color:var(--muted-2)}
.landing-note{font-size:13.4px;color:var(--muted);border-left:3px solid var(--accent-soft);padding:2px 0 2px 12px;margin:0 0 10px}

/* сайдбар: список предметов */
.subj-nav{list-style:none;margin:0 0 4px;padding:0}
.subj-nav a{display:flex;gap:9px;align-items:center;padding:7px 8px;border-radius:var(--radius-sm);color:var(--ink-2)}
.subj-nav a:hover{background:var(--surface-2);text-decoration:none}
.subj-nav a.active{background:var(--accent-soft);color:var(--accent-ink);font-weight:600}
.subj-nav a.soon{color:var(--muted-2);pointer-events:none}
.subj-mark{flex:none;width:24px;height:24px;border-radius:7px;display:grid;place-items:center;font-size:12.5px;font-weight:650;color:#fff;background:#94a3b8}
.subj-nav a.active .subj-mark,.subj-nav a:not(.soon) .subj-mark{background:linear-gradient(160deg,#3b82f6,#1d4ed8)}
.back-all{display:inline-flex;align-items:center;gap:6px;font-size:13px;color:var(--muted);margin-bottom:10px}
.sidebar-subj{font-size:15px;font-weight:650;padding:0 8px 8px;color:var(--ink)}

/* на главной поиск и прогресс не нужны */
body.no-subject .search-wrap,
body.no-subject .topbar-progress{display:none}
/* на главной нечего сбрасывать и рано показывать выходные данные учебника */
body.no-subject .sidebar-foot{display:none}

/* три преимущества на главной */
.features{display:grid;grid-template-columns:repeat(auto-fit,minmax(196px,1fr));gap:12px;margin:0 0 16px}
.feature{
  border:1px solid var(--line);border-radius:13px;padding:14px 16px;
  background:linear-gradient(180deg,#fff,#f8fbfe);
  box-shadow:0 1px 2px rgba(16,24,40,.04),0 12px 28px -22px rgba(16,24,40,.30);
}
.feature b{display:block;font-size:14.8px;margin-bottom:3px}
.feature span{font-size:13.2px;color:var(--muted);line-height:1.5}