:root{
  --bg:#F5F6F8; --surface:#FFFFFF; --ink:#1A1E29; --muted:#6A7080; --line:#DDE0E7; --locked:#ECEEF2;
  --accent:#2F55D4; --accent-ink:#FFFFFF;
  --good:#1E8A52; --good-bg:#E6F4EC; --bad:#C4362E; --heart:#E5484D;
}
@media (prefers-color-scheme: dark){
  :root{
    color-scheme:dark;
    --bg:#12151C; --surface:#1B1F29; --ink:#E9ECF2; --muted:#9097A6; --line:#2C3140; --locked:#171A22;
    --accent:#6E8CFF; --accent-ink:#0E1220;
    --good:#5CCB8E; --good-bg:#16291F; --bad:#FF7F75; --heart:#FF6B70;
  }
}
*{box-sizing:border-box}
[hidden]{display:none!important}
body{
  margin:0; background:var(--bg); color:var(--ink);
  font-family:"Golos Text",system-ui,-apple-system,"Segoe UI",sans-serif; font-size:16px;
  padding-inline:16px; padding-block:32px;
}
.wrap{max-width:720px;margin:0 auto;display:flex;flex-direction:column;gap:18px}
header{display:flex;align-items:baseline;justify-content:space-between;gap:12px;flex-wrap:wrap}
h1{font-family:"Unbounded","Golos Text",sans-serif;font-weight:700;font-size:clamp(22px,4vw,30px);margin:0;letter-spacing:-.01em;text-wrap:balance}
.sub{margin:-8px 0 4px;color:var(--muted);font-size:14px;line-height:1.5}
.back{color:var(--muted);text-decoration:none;font-size:14px}
.back:hover{color:var(--ink)}
.state{color:var(--muted);padding:24px 0}
.state.err{color:var(--bad)}

/* список домашек */
.list{display:flex;flex-direction:column;gap:12px}
.hw{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:20px 22px;border-radius:12px;border:1px solid var(--line);background:var(--surface);color:inherit;text-decoration:none;transition:border-color .15s,transform .15s}
a.hw:hover{border-color:var(--accent);transform:translateY(-1px)}
a.hw:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.hw.locked{background:var(--locked);border-color:transparent;cursor:not-allowed}
.hw-title{font-family:"Unbounded","Golos Text",sans-serif;font-weight:500;font-size:clamp(17px,3vw,21px)}
.hw.locked .hw-title{color:var(--muted)}
.hw-meta{font-size:14px;color:var(--muted);margin-top:6px}
.hw-side{display:flex;flex-direction:column;align-items:flex-end;gap:6px;flex-shrink:0;font-size:14px;color:var(--muted);font-variant-numeric:tabular-nums}
.bar{width:90px;height:6px;border-radius:3px;background:var(--line);overflow:hidden}
.bar i{display:block;height:100%;background:var(--good)}
.arrow{font-size:22px;color:var(--accent)}
.lock{width:20px;height:20px;fill:none;stroke:var(--muted);stroke-width:2}

/* задания */
.progress{font-size:14px;color:var(--muted);font-variant-numeric:tabular-nums}
.progress b{font-family:"Unbounded",sans-serif;color:var(--ink);font-size:20px;margin:0 2px}
.task{background:var(--surface);border:1px solid var(--line);border-radius:12px;padding:22px 24px;display:flex;flex-direction:column;gap:16px;transition:border-color .3s}
.task.ok{border-color:var(--good)}
.task.no{border-color:var(--bad)}
.top{display:flex;justify-content:space-between;align-items:center;gap:12px}
.num{font-family:"Unbounded",sans-serif;font-weight:500;font-size:15px;color:var(--accent)}
.num span{font-family:"Golos Text",sans-serif;font-size:13px;color:var(--muted);text-transform:uppercase;letter-spacing:.08em;font-weight:600;margin-left:8px}
.hearts{display:flex;gap:4px}
.hearts svg{width:26px;height:26px;display:block}
.hearts svg path{fill:var(--heart);stroke:var(--heart);stroke-width:1.5}
.hearts svg.gone path{fill:none;stroke:var(--line)}
.hearts svg.lost{animation:lose .5s}
@keyframes lose{0%{transform:scale(1)}30%{transform:scale(1.35)}100%{transform:scale(1)}}
.q{font-size:18px;line-height:1.6;text-wrap:pretty}
.q.math{font-size:clamp(22px,4vw,30px);text-align:center;line-height:2}
.q .intro{font-size:15px;color:var(--muted);line-height:1.4;margin-bottom:6px}
.row{display:flex;gap:10px;flex-wrap:wrap}
.row input{flex:1 1 160px;min-width:0;font:inherit;font-size:19px;padding:10px 14px;border-radius:9px;border:1px solid var(--line);background:var(--bg);color:var(--ink)}
.row input:focus{outline:2px solid var(--accent);outline-offset:0;border-color:transparent}
.row input:disabled{opacity:.65}
.btn{font:inherit;font-size:15px;font-weight:500;padding:10px 18px;border-radius:9px;cursor:pointer;border:1px solid var(--accent);background:var(--accent);color:var(--accent-ink)}
.btn{text-decoration:none;display:inline-block}
.btn:disabled{opacity:.6;cursor:wait}
.btn:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
.msg{font-size:14px;color:var(--muted);min-height:1.2em;line-height:1.5}
.msg.err{color:var(--bad)} .msg.ok{color:var(--good);font-weight:600;font-size:16px} .msg.no{color:var(--bad);font-weight:600;font-size:16px}
.shake{animation:shake .35s}
@keyframes shake{20%,60%{transform:translateX(-6px)}40%,80%{transform:translateX(6px)}}

.frac{display:inline-flex;flex-direction:column;align-items:center;vertical-align:middle;margin:0 .12em;line-height:1.1;font-size:.9em}
.frac>span{padding:0 .2em}
.frac>span:first-child{border-bottom:.08em solid currentColor;padding-bottom:.06em}
.frac>span:last-child{padding-top:.06em}
.x{font-style:italic;font-family:Georgia,"Times New Roman",serif}

.cele{position:fixed;inset:0;z-index:20;pointer-events:none;display:flex;align-items:center;justify-content:center}
.cele canvas{position:absolute;inset:0;width:100%;height:100%}
.cele .big{position:relative;font-family:"Unbounded","Golos Text",sans-serif;font-weight:700;font-size:clamp(56px,14vw,140px);line-height:1;color:var(--good);text-shadow:0 6px 30px rgba(0,0,0,.18);animation:pop 1.6s cubic-bezier(.2,1.4,.4,1) both}
@keyframes pop{0%{transform:scale(.3);opacity:0}18%{transform:scale(1.08);opacity:1}30%{transform:scale(1)}78%{transform:scale(1);opacity:1}100%{transform:scale(1.04) translateY(-20px);opacity:0}}
@keyframes fade{0%,80%{opacity:1}100%{opacity:0}}
@media (max-width:480px){ .task{padding:18px} .hearts svg{width:22px;height:22px} .hw{padding:18px} }
@media (prefers-reduced-motion:reduce){ .cele .big{animation:fade 1.6s both} .shake,.hearts svg.lost{animation:none} .hw{transition:none} }

/* шапка с именем и выходом */
.topbar{display:flex;justify-content:flex-end;align-items:center;gap:14px;font-size:14px;color:var(--muted);min-height:20px}
.topbar .who{color:var(--ink);font-weight:500}
.link{background:none;border:0;padding:0;font:inherit;color:var(--accent);cursor:pointer;text-decoration:none}
.link:hover{text-decoration:underline}
.link:focus-visible{outline:2px solid var(--accent);outline-offset:2px;border-radius:3px}

/* вход */
.login{max-width:380px;margin:8vh auto 0;display:flex;flex-direction:column;gap:22px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:14px;padding:26px 24px;display:flex;flex-direction:column;gap:16px}
.field{display:flex;flex-direction:column;gap:6px}
.field label{font-size:13px;color:var(--muted);font-weight:600;text-transform:uppercase;letter-spacing:.06em}
.field input{font:inherit;font-size:18px;padding:11px 14px;border-radius:9px;border:1px solid var(--line);background:var(--bg);color:var(--ink);min-width:0;width:100%}
.field input:focus{outline:2px solid var(--accent);outline-offset:0;border-color:transparent}
.field input.code{font-family:ui-monospace,"SF Mono",Menlo,monospace;letter-spacing:.18em;text-transform:uppercase}
.btn.wide{width:100%;padding:12px 18px;font-size:16px}
.btn.ghost{background:none;color:var(--accent)}
.btn.danger{background:none;border-color:var(--bad);color:var(--bad)}

/* кабинет Александры */
.students{display:flex;flex-direction:column;gap:12px}
.st{display:grid;grid-template-columns:1fr;gap:14px;padding:18px 22px;border-radius:12px;border:1px solid var(--line);background:var(--surface)}
.st-name{font-family:"Unbounded","Golos Text",sans-serif;font-weight:500;font-size:19px}
.st-meta{font-size:14px;color:var(--muted);margin-top:6px;line-height:1.6}
.st-actions{display:flex;gap:16px;flex-wrap:wrap;align-items:center}
.chip{display:inline-flex;align-items:center;gap:8px;font-family:ui-monospace,"SF Mono",Menlo,monospace;font-size:15px;letter-spacing:.12em;padding:4px 10px;border-radius:7px;background:var(--bg);border:1px solid var(--line);color:var(--ink)}
.section-title{font-family:"Unbounded","Golos Text",sans-serif;font-weight:500;font-size:17px;margin:14px 0 0}
.formrow{display:flex;gap:12px;flex-wrap:wrap;align-items:flex-end}
.formrow .field{flex:1 1 180px}
.note{font-size:14px;color:var(--muted);line-height:1.5}
.note.ok{color:var(--good)} .note.err{color:var(--bad)}
.confirm{display:flex;gap:10px;align-items:center;flex-wrap:wrap;font-size:14px;color:var(--bad)}
.badge{display:inline-block;font-size:12px;font-weight:600;letter-spacing:.04em;padding:2px 8px;border-radius:6px;background:var(--locked);color:var(--muted);vertical-align:middle;margin-left:6px}

/* разбор домашки для Александры */
.log{display:flex;flex-wrap:wrap;gap:6px}
.log span{font-size:14px;padding:3px 9px;border-radius:6px;border:1px solid var(--line);font-variant-numeric:tabular-nums}
.log span.ok{border-color:var(--good);color:var(--good)}
.log span.no{border-color:var(--bad);color:var(--bad);text-decoration:line-through;text-decoration-thickness:1px}
.ans{font-size:16px;color:var(--muted);line-height:1.8}
.ans b{color:var(--ink);font-weight:600}

/* сдача домашки */
.submit{display:flex;flex-direction:column;gap:10px;margin-top:6px}
.submit.done{flex-direction:row;flex-wrap:wrap;gap:6px 10px;align-items:baseline;padding:16px 20px;border-radius:12px;background:var(--good-bg);color:var(--good);font-size:15px}
.submit.done span{color:var(--ink)}
.task.closed{opacity:.75}
.pill{display:inline-block;font-size:12px;font-weight:600;padding:2px 9px;border-radius:999px;background:var(--good-bg);color:var(--good);margin-left:8px;vertical-align:middle;font-family:"Golos Text",sans-serif}
.bigheart{display:flex;align-items:center;justify-content:center;min-height:calc(100vh - 160px)}
.bigheart svg{width:min(92vw,78vh);height:min(92vw,78vh);display:block;animation:beat 1.4s ease-in-out infinite}
.bigheart svg path{fill:var(--heart)}
@keyframes beat{0%,60%,100%{transform:scale(1)}20%{transform:scale(1.07)}40%{transform:scale(.97)}}
@media (prefers-reduced-motion:reduce){ .bigheart svg{animation:none} }
.heartmark{color:var(--heart);font-size:24px;line-height:1}
.pill.wait{background:var(--locked);color:var(--muted)}