/* Layout: лист в клетку — липкая шапка, широкие секции в одной колонке 1120px, карточки сеткой auto-fit */
:root{
  --paper:#f5f8fc;
  --card:#ffffff;
  --grid:rgba(37,99,163,.10);
  --ink:#16263d;          /* синяя паста */
  --ink-soft:#52647e;
  --line:#dbe4ef;
  --accent:#1f5fb0;       /* ручка */
  --accent-soft:#e8f0fb;
  --pen:#c62f3b;          /* красная ручка учителя */
  --ok:#1d7a52;
  --mark:#f7d774;         /* маркер */
  --shadow:0 1px 2px rgba(22,38,61,.06),0 8px 24px rgba(22,38,61,.06);
  --strip:#13263f;--strip-fg:#b9cde8;
  --display:"Literata",Georgia,"Times New Roman",serif;
  --body:"Golos Text",-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;
}
@media (prefers-color-scheme:dark){
  :root:not([data-theme="light"]){
    --paper:#0e141d; --card:#151d29; --grid:rgba(120,170,230,.07);
    --ink:#e6edf6; --ink-soft:#97a7bd; --line:#26323f;
    --accent:#6ea8f0; --accent-soft:#1b2838; --pen:#f0737d; --ok:#56c48e; --mark:#8a7430;
    --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 28px rgba(0,0,0,.35);
    --strip:#070b11;--strip-fg:#8fa3bd;
    color-scheme:dark;
  }
}
:root[data-theme="dark"]{
  --paper:#0e141d; --card:#151d29; --grid:rgba(120,170,230,.07);
  --ink:#e6edf6; --ink-soft:#97a7bd; --line:#26323f;
  --accent:#6ea8f0; --accent-soft:#1b2838; --pen:#f0737d; --ok:#56c48e; --mark:#8a7430;
  --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 28px rgba(0,0,0,.35);
  --strip:#070b11;--strip-fg:#8fa3bd;
  color-scheme:dark;
}
*{box-sizing:border-box}
body{
  margin:0;background:var(--paper);color:var(--ink);font-family:var(--body);
  font-size:16px;line-height:1.6;-webkit-font-smoothing:antialiased;
  background-image:linear-gradient(var(--grid) 1px,transparent 1px),linear-gradient(90deg,var(--grid) 1px,transparent 1px);
  background-size:26px 26px;
}
.wrap{max-width:1120px;margin:0 auto;padding-inline:18px}
h1,h2,h3{font-family:var(--display);font-weight:700;text-wrap:balance;margin:0;line-height:1.2}
h1{font-size:clamp(30px,6.2vw,52px);letter-spacing:-.01em}
h2{font-size:clamp(22px,4vw,32px)}
h3{font-size:18px}
p{margin:0}
a{color:inherit}
.eyebrow{font-size:12px;letter-spacing:.1em;text-transform:uppercase;color:var(--accent);font-weight:600}

/* шапка */
.utility{background:var(--strip);color:var(--strip-fg);font-size:12.5px}
.utility .wrap{display:flex;align-items:center;gap:16px;height:36px;white-space:nowrap;overflow:hidden}
.utility b{color:#fff;font-weight:600}
.utility .u-right{margin-left:auto;display:flex;align-items:center;gap:16px}
.utility a{color:var(--strip-fg);text-decoration:none}
.utility a:hover{color:#fff}
.u-dot{width:6px;height:6px;border-radius:50%;background:#53c08a;display:inline-block;margin-right:6px;vertical-align:1px;animation:pulse 2.6s ease-in-out infinite}
@keyframes pulse{0%,100%{opacity:1}50%{opacity:.35}}
.themeBtn{background:none;border:1px solid rgba(255,255,255,.18);color:var(--strip-fg);border-radius:7px;width:26px;height:26px;cursor:pointer;font-size:13px;line-height:1;display:grid;place-items:center}
.themeBtn:hover{color:#fff;border-color:rgba(255,255,255,.4)}
@media(max-width:620px){.utility .u-sep,.utility .u-hide{display:none}}

header.top{position:sticky;top:env(safe-area-inset-top,0px);z-index:40;background:color-mix(in srgb,var(--paper) 90%,transparent);backdrop-filter:blur(12px);border-bottom:1px solid var(--line);transition:box-shadow .2s}
header.top.scrolled{box-shadow:0 6px 20px rgba(22,38,61,.08)}
.top .wrap{display:flex;align-items:center;gap:14px;height:72px;transition:height .2s}
header.top.scrolled .top-row{height:60px}
.logo{display:flex;align-items:center;gap:10px;font-family:var(--display);font-weight:700;font-size:19px;text-decoration:none;white-space:nowrap;letter-spacing:-.01em}
.logo .glyph{width:34px;height:34px;border-radius:9px;background:var(--accent);color:#fff;display:grid;place-items:center;font-size:17px;flex:none;box-shadow:0 2px 0 color-mix(in srgb,var(--accent) 70%,#000)}
.logo small{display:block;font-family:var(--body);font-size:10.5px;font-weight:500;letter-spacing:.09em;text-transform:uppercase;color:var(--ink-soft);margin-top:1px}
nav.main{display:flex;align-items:center;gap:4px;margin-left:22px;font-size:15px;font-weight:500}
nav.main>a,.navBtn{display:flex;align-items:center;gap:5px;text-decoration:none;color:var(--ink);padding:9px 12px;border-radius:9px;background:none;border:0;font:500 15px/1 var(--body);cursor:pointer}
nav.main>a:hover,.navBtn:hover{background:var(--accent-soft);color:var(--accent)}
.navBtn .caret{font-size:10px;color:var(--ink-soft);transition:transform .18s}
.has-menu.open .navBtn .caret{transform:rotate(180deg)}
.has-menu{position:relative}
.menu{position:absolute;top:calc(100% + 10px);left:-8px;width:420px;background:var(--card);border:1px solid var(--line);border-radius:14px;box-shadow:var(--shadow);padding:16px;opacity:0;visibility:hidden;transform:translateY(-6px);transition:.16s;z-index:50}
.has-menu.open .menu{opacity:1;visibility:visible;transform:none}
.menu h5{margin:0 0 9px;font:600 11.5px/1 var(--body);letter-spacing:.09em;text-transform:uppercase;color:var(--ink-soft)}
.menu-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:7px}
.menu-grid button{border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:9px;padding:9px 0;font:600 14px/1 var(--body);cursor:pointer}
.menu-grid button:hover{border-color:var(--accent);color:var(--accent)}
.menu-list{display:grid;gap:2px;margin-top:14px;padding-top:12px;border-top:1px solid var(--line)}
.menu-list button{text-align:left;border:0;background:none;color:var(--ink);padding:8px 9px;border-radius:8px;font:500 14.5px/1.3 var(--body);cursor:pointer;display:flex;justify-content:space-between;gap:10px}
.menu-list button:hover{background:var(--accent-soft);color:var(--accent)}
.menu-list span{color:var(--ink-soft);font-size:13px;font-variant-numeric:tabular-nums}
.head-actions{margin-left:auto;display:flex;align-items:center;gap:9px}
.burger{display:none;width:40px;height:40px;border:1px solid var(--line);background:var(--card);border-radius:10px;cursor:pointer;color:var(--ink);font-size:17px;line-height:1}
.progress{position:absolute;left:0;bottom:-1px;height:2px;width:0;background:var(--accent);transition:width .1s linear}
@media(max-width:900px){nav.main{display:none}.burger{display:grid;place-items:center}.head-actions .btn{display:none}}

/* мобильное меню */
.drawer{position:fixed;inset:0;z-index:60;background:rgba(10,18,30,.45);opacity:0;visibility:hidden;transition:.18s}
.drawer.open{opacity:1;visibility:visible}
.drawer-panel{position:absolute;right:0;top:0;bottom:0;width:min(330px,86vw);background:var(--card);border-left:1px solid var(--line);padding:18px;padding-top:calc(18px + env(safe-area-inset-top,0px));overflow-y:auto;transform:translateX(12px);transition:transform .2s}
.drawer.open .drawer-panel{transform:none}
.drawer-head{display:flex;align-items:center;justify-content:space-between;margin-bottom:18px}
.drawer-panel nav{display:grid;gap:2px;margin-bottom:18px}
.drawer-panel nav a{text-decoration:none;color:var(--ink);padding:12px 10px;border-radius:9px;font-weight:500;border-bottom:1px solid var(--line)}
.drawer-panel nav a:last-child{border-bottom:0}
.closeBtn{border:1px solid var(--line);background:var(--paper);color:var(--ink);width:36px;height:36px;border-radius:9px;cursor:pointer;font-size:17px}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;border:1px solid transparent;border-radius:10px;padding:11px 18px;font:600 15px/1 var(--body);cursor:pointer;text-decoration:none;transition:.15s}
.btn-primary{background:var(--accent);color:#fff}
.btn-primary:hover{filter:brightness(1.08)}
.btn-ghost{background:transparent;border-color:var(--line);color:var(--ink)}
.btn-ghost:hover{border-color:var(--accent);color:var(--accent)}
.btn-sm{padding:8px 13px;font-size:14px;border-radius:9px}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}

/* герой */
.hero{padding-block:clamp(38px,7vw,74px) 30px;display:grid;grid-template-columns:1.15fr .85fr;gap:44px;align-items:center}
@media(max-width:860px){.hero{grid-template-columns:1fr;gap:28px}}
.hero p.lead{font-size:clamp(16px,2.3vw,18.5px);color:var(--ink-soft);margin-top:16px;max-width:52ch}
.hero-actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:24px}
.facts{display:flex;flex-wrap:wrap;gap:22px;margin-top:28px;padding-top:22px;border-top:1px solid var(--line)}
.fact b{display:block;font-family:var(--display);font-size:24px;font-variant-numeric:tabular-nums}
.fact span{font-size:13px;color:var(--ink-soft)}
.hl{background:linear-gradient(transparent 62%,var(--mark) 62%);padding-inline:2px}

/* карточка-превью урока */
.preview{background:var(--card);border:1px solid var(--line);border-radius:16px;box-shadow:var(--shadow);overflow:hidden}
.preview .bar{display:flex;align-items:center;gap:7px;padding:11px 14px;border-bottom:1px solid var(--line);font-size:12.5px;color:var(--ink-soft)}
.dot{width:9px;height:9px;border-radius:50%;background:var(--line)}
.preview .body{padding:18px}
.step{display:flex;gap:11px;padding:9px 0;align-items:flex-start;font-size:14.5px}
.step .n{flex:none;width:21px;height:21px;border-radius:50%;background:var(--accent-soft);color:var(--accent);font:600 12px/21px var(--body);text-align:center}
.formula{font-family:var(--display);font-size:17px}
.redpen{color:var(--pen);font-size:13.5px;border-left:2px solid var(--pen);padding-left:9px;margin-top:10px;font-style:italic}

/* секции */
section{padding-block:clamp(40px,6vw,66px);scroll-margin-top:74px}
.sec-head{max-width:62ch;margin-bottom:26px}
.sec-head p{color:var(--ink-soft);margin-top:9px}

/* фильтры каталога */
.filters{display:flex;flex-wrap:wrap;gap:9px;align-items:center;margin-bottom:18px}
.search{flex:1 1 230px;min-width:0;display:flex;align-items:center;gap:8px;background:var(--card);border:1px solid var(--line);border-radius:10px;padding:0 12px}
.search input{flex:1;min-width:0;border:0;background:transparent;color:var(--ink);font:400 15px/1 var(--body);padding:11px 0}
.search input:focus{outline:none}
.chips{display:flex;flex-wrap:wrap;gap:7px}
.chip{border:1px solid var(--line);background:var(--card);color:var(--ink-soft);border-radius:999px;padding:7px 13px;font:500 14px/1 var(--body);cursor:pointer;transition:.12s}
.chip:hover{border-color:var(--accent)}
.chip[aria-pressed="true"]{background:var(--accent);border-color:var(--accent);color:#fff}
.grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(258px,1fr));gap:14px}
.topic{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:16px;display:flex;flex-direction:column;gap:9px;min-width:0;transition:.15s}
.topic:hover{border-color:var(--accent);transform:translateY(-2px)}
.topic .tags{display:flex;gap:6px;flex-wrap:wrap}
.tag{font-size:11.5px;font-weight:600;letter-spacing:.03em;padding:3px 8px;border-radius:6px;background:var(--accent-soft);color:var(--accent)}
.tag.sec{background:transparent;border:1px solid var(--line);color:var(--ink-soft);font-weight:500}
.topic h3{font-size:16.5px;font-family:var(--body);font-weight:600;line-height:1.35}
.topic .meta{margin-top:auto;display:flex;gap:14px;font-size:13px;color:var(--ink-soft);font-variant-numeric:tabular-nums}
.empty{padding:28px;text-align:center;color:var(--ink-soft);border:1px dashed var(--line);border-radius:14px}

/* тренажёр */
.trainer{background:var(--card);border:1px solid var(--line);border-radius:18px;box-shadow:var(--shadow);overflow:hidden}
.trainer-head{padding:16px 18px;border-bottom:1px solid var(--line);display:flex;flex-wrap:wrap;gap:10px;align-items:center}
.trainer-head .streak{margin-left:auto;font-size:13.5px;color:var(--ink-soft);font-variant-numeric:tabular-nums}
.task{padding:26px 18px;text-align:center}
.task .q{font-family:var(--display);font-size:clamp(24px,5.5vw,34px);line-height:1.35;margin-bottom:6px}
.task .hint{font-size:13.5px;color:var(--ink-soft)}
.answer{display:flex;gap:9px;justify-content:center;margin-top:20px;flex-wrap:wrap}
.answer input{width:150px;max-width:60vw;border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:10px;padding:12px 14px;font:600 17px/1 var(--display);text-align:center}
.verdict{margin-top:16px;font-size:15px;font-weight:600;min-height:24px}
.verdict.ok{color:var(--ok)}
.verdict.no{color:var(--pen)}
.solution{margin:14px auto 0;max-width:430px;text-align:left;background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:14px;font-size:14.5px}
.solution b{font-family:var(--display)}

/* две колонки «как это работает» */
.cols{display:grid;grid-template-columns:repeat(auto-fit,minmax(250px,1fr));gap:16px}
.col{background:var(--card);border:1px solid var(--line);border-radius:14px;padding:18px;min-width:0}
.col .ico{width:34px;height:34px;border-radius:9px;background:var(--accent-soft);color:var(--accent);display:grid;place-items:center;font-size:17px;margin-bottom:11px}
.col h3{font-family:var(--body);font-size:16px;margin-bottom:6px}
.col p{font-size:14.5px;color:var(--ink-soft)}

/* блок для учителя */
.teacher{border-top:3px solid var(--pen)}
.builder{background:var(--card);border:1px solid var(--line);border-radius:16px;padding:18px;display:grid;grid-template-columns:260px 1fr;gap:18px;min-width:0}
@media(max-width:760px){.builder{grid-template-columns:1fr}}
.field{margin-bottom:13px}
.field label{display:block;font-size:13px;font-weight:600;color:var(--ink-soft);margin-bottom:6px}
.field select,.field input[type=number]{width:100%;border:1px solid var(--line);background:var(--paper);color:var(--ink);border-radius:9px;padding:10px 11px;font:500 14.5px/1 var(--body)}
.sheet{background:var(--paper);border:1px solid var(--line);border-radius:12px;padding:18px;min-width:0;overflow-x:auto}
.sheet h4{font-family:var(--display);font-size:17px;margin:0 0 3px}
.sheet .sub{font-size:12.5px;color:var(--ink-soft);margin-bottom:14px;padding-bottom:10px;border-bottom:1px dashed var(--line)}
.sheet ol{margin:0;padding-left:22px}
.sheet li{font-family:var(--display);font-size:15.5px;padding:7px 0;border-bottom:1px dotted var(--line)}
.sheet-actions{display:flex;gap:9px;margin-top:14px;flex-wrap:wrap}

/* FAQ */
details{background:var(--card);border:1px solid var(--line);border-radius:12px;padding:14px 16px;margin-bottom:9px}
details[open]{border-color:var(--accent)}
summary{cursor:pointer;font-weight:600;font-size:15.5px;list-style:none;display:flex;justify-content:space-between;gap:12px}
summary::-webkit-details-marker{display:none}
summary::after{content:"+";color:var(--accent);font-size:20px;line-height:1}
details[open] summary::after{content:"–"}
details p{margin-top:10px;font-size:14.5px;color:var(--ink-soft)}

/* CTA + футер */
.cta{background:var(--accent);color:#fff;border-radius:20px;padding:clamp(26px,5vw,44px);text-align:center}
.cta h2{color:#fff}
.cta p{color:rgba(255,255,255,.85);margin:10px auto 22px;max-width:48ch}
.cta .btn-primary{background:#fff;color:var(--accent)}
footer{background:var(--strip);color:var(--strip-fg);margin-top:60px;padding-block:0 30px;position:relative}
.foot-top{display:flex;align-items:flex-end;justify-content:space-between;gap:20px;padding-block:34px 28px;border-bottom:1px solid rgba(255,255,255,.1);flex-wrap:wrap}
.foot-brand{display:flex;align-items:center;gap:12px}
.foot-brand .glyph{width:40px;height:40px;border-radius:11px;background:var(--accent);color:#fff;display:grid;place-items:center;font-size:20px;font-family:var(--display);flex:none}
.foot-brand strong{display:block;font-family:var(--display);font-size:21px;color:#fff}
.foot-brand span{font-size:13.5px}
.toTop{display:inline-flex;align-items:center;gap:8px;border:1px solid rgba(255,255,255,.2);border-radius:999px;padding:9px 16px;font-size:13.5px;color:var(--strip-fg);text-decoration:none;background:none;cursor:pointer;font-family:var(--body)}
.toTop:hover{border-color:rgba(255,255,255,.5);color:#fff}
.foot{display:grid;grid-template-columns:1.3fr 1fr 1fr 1.2fr;gap:28px;padding-block:30px}
@media(max-width:820px){.foot{grid-template-columns:1fr 1fr;gap:26px}}
@media(max-width:460px){.foot{grid-template-columns:1fr}.foot-top{padding-block:26px 22px}}
.foot h4{font-size:11.5px;text-transform:uppercase;letter-spacing:.1em;color:#fff;margin:0 0 13px;font-family:var(--body);font-weight:600}
.foot ul{list-style:none;margin:0;padding:0;display:grid;gap:9px;font-size:14.5px}
.foot a,.foot button.link{color:var(--strip-fg);text-decoration:none;background:none;border:0;padding:0;font:400 14.5px/1.4 var(--body);cursor:pointer;text-align:left}
.foot a:hover,.foot button.link:hover{color:#fff}
.classRow{display:flex;flex-wrap:wrap;gap:6px}
.classRow button{border:1px solid rgba(255,255,255,.16);background:rgba(255,255,255,.04);color:var(--strip-fg);border-radius:8px;min-width:38px;padding:8px 9px;font:600 13.5px/1 var(--body);cursor:pointer}
.classRow button:hover{border-color:var(--accent);background:var(--accent);color:#fff}
.foot-note{font-size:13.5px;line-height:1.6;margin-bottom:14px}
.contact{display:flex;align-items:center;gap:8px;background:rgba(255,255,255,.05);border:1px solid rgba(255,255,255,.12);border-radius:10px;padding:10px 12px;margin-bottom:9px}
.contact .mono{font-family:var(--display);font-size:14px;color:#fff;user-select:all;overflow:hidden;text-overflow:ellipsis}
.contact button{margin-left:auto;background:none;border:0;color:var(--strip-fg);cursor:pointer;font-size:12.5px;white-space:nowrap;font-family:var(--body)}
.contact button:hover{color:#fff}
.copy{padding-top:20px;border-top:1px solid rgba(255,255,255,.1);font-size:12.5px;display:flex;flex-wrap:wrap;gap:8px 18px;align-items:center}
.copy .spacer{margin-left:auto}
.copy a{color:var(--strip-fg);text-decoration:none}
.copy a:hover{color:#fff}
@media (prefers-reduced-motion:reduce){*{transition:none!important;animation:none!important}}