:root {
  --bg: #f4f5f8;
  --card: #ffffff;
  --ink: #15192b;
  --muted: #5d647a;
  --line: #dfe2ea;
  --accent: #2545d3;
  --accent-ink: #ffffff;
  --accent-soft: #e8ecfd;
  --ok: #17794a;
  --ok-soft: #e2f4ea;
  --warn: #a15c00;
  --warn-soft: #fdf0d9;
  --bad: #b3261e;
  --bad-soft: #fbe6e4;
  --radius: 14px;
  --shadow: 0 1px 2px rgba(21, 25, 43, .06), 0 8px 24px rgba(21, 25, 43, .06);
  color-scheme: light dark;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1220;
    --card: #181c2e;
    --ink: #eceef6;
    --muted: #9aa1b9;
    --line: #2a3048;
    --accent: #7f95ff;
    --accent-ink: #0c1024;
    --accent-soft: #222a52;
    --ok: #5fd39a;
    --ok-soft: #143325;
    --warn: #f0b861;
    --warn-soft: #3a2c12;
    --bad: #ff8a80;
    --bad-soft: #3d1a18;
    --shadow: none;
  }
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  min-height: 100vh;
}

h1, h2, h3 { line-height: 1.25; margin: 0; text-wrap: balance; }
h1 { font-size: 1.5rem; }
h2 { font-size: 1.2rem; }
p { margin: 0; }
[hidden] { display: none !important; }

.wrap { max-width: 720px; margin: 0 auto; padding: 24px 16px 48px; }
.wrap.wide { max-width: 1180px; }

.top {
  display: flex; align-items: baseline; justify-content: space-between; gap: 12px;
  margin-bottom: 20px; flex-wrap: wrap;
}
.brand { font-weight: 700; letter-spacing: -.01em; }
.brand small { display: block; font-weight: 400; color: var(--muted); font-size: .85rem; }
.eyebrow {
  margin: 0 0 10px 2px; font-size: .8rem; font-weight: 700; letter-spacing: .06em;
  text-transform: uppercase; color: var(--accent);
}
.who { color: var(--muted); font-size: .9rem; text-align: right; }

.card {
  background: var(--card); border: 1px solid var(--line); border-radius: var(--radius);
  box-shadow: var(--shadow); padding: 24px;
}
.card + .card, .card.mt { margin-top: 16px; }
.card.narrow { max-width: 420px; margin-left: auto; margin-right: auto; }
.stack > * + * { margin-top: 14px; }
.muted { color: var(--muted); }
.small { font-size: .875rem; }
.center { text-align: center; }

label { display: block; font-weight: 600; font-size: .9rem; margin-bottom: 6px; }
input[type=text], input[type=email], input[type=password] {
  width: 100%; padding: 12px 14px; font: inherit; color: var(--ink);
  background: var(--bg); border: 1px solid var(--line); border-radius: 10px;
}
input:focus-visible, button:focus-visible, a:focus-visible {
  outline: 3px solid var(--accent-soft); outline-offset: 1px; border-color: var(--accent);
}
input::placeholder { color: var(--muted); opacity: .45; }
input.code {
  font-size: 1.8rem; letter-spacing: .4em; text-align: center;
  font-variant-numeric: tabular-nums; font-weight: 700;
}

button, a.btn {
  font: inherit; font-weight: 600; cursor: pointer; border-radius: 10px;
  padding: 12px 18px; border: 1px solid transparent;
  background: var(--accent); color: var(--accent-ink);
}
button:hover:not(:disabled) { filter: brightness(1.08); }
button:disabled { opacity: .5; cursor: not-allowed; }
button.block { width: 100%; }
button.ghost { background: transparent; color: var(--accent); border-color: var(--line); }
button.link { background: none; border: 0; padding: 0; color: var(--accent); font-weight: 500; }
a.btn { text-decoration: none; display: inline-block; }
a.btn.ghost { background: transparent; color: var(--accent); border-color: var(--line); }
button.sm, a.btn.sm { padding: 6px 10px; font-size: .85rem; border-radius: 8px; }
button.danger { background: transparent; color: var(--bad); border-color: var(--line); }

.msg { padding: 10px 14px; border-radius: 10px; font-size: .92rem; }
.msg.err { background: var(--bad-soft); color: var(--bad); }
.msg.info { background: var(--accent-soft); color: var(--ink); }

.rules { margin: 0; padding-left: 20px; }
.rules li + li { margin-top: 6px; }

.pulse {
  width: 12px; height: 12px; border-radius: 50%; background: var(--warn);
  display: inline-block; margin-right: 8px; animation: pulse 1.6s ease-in-out infinite;
}
@keyframes pulse { 50% { opacity: .25; } }
@media (prefers-reduced-motion: reduce) { .pulse { animation: none; } }

/* --- вопрос --- */
.qsticky {
  position: sticky; top: 0; z-index: 2; background: var(--card);
  margin: -12px -8px 0; padding: 12px 8px 10px;
}
.qsticky .bar { margin-top: 10px; }
.qhead { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.qnum { color: var(--muted); font-weight: 600; font-size: .9rem; }
.timer {
  font-variant-numeric: tabular-nums; font-weight: 700; font-size: 1.15rem;
  padding: 4px 12px; border-radius: 999px; background: var(--accent-soft); color: var(--accent);
}
.timer.low { background: var(--bad-soft); color: var(--bad); }
.bar { height: 6px; background: var(--line); border-radius: 999px; overflow: hidden; }
.bar > i { display: block; height: 100%; width: 100%; background: var(--accent); transform-origin: left; }
.bar.low > i { background: var(--bad); }
.stem { font-size: 1.2rem; font-weight: 700; }
.qkind {
  display: inline-block; padding: 4px 12px; border-radius: 8px; font-size: .85rem; font-weight: 700;
  background: var(--warn-soft); color: var(--warn);
}

.exam, .exam * { user-select: none; -webkit-user-select: none; }
.options { display: grid; gap: 10px; }
.opt {
  display: grid; grid-template-columns: 28px 1fr; gap: 12px; align-items: start;
  text-align: left; width: 100%; padding: 14px 16px; font-weight: 400; line-height: 1.45;
  background: var(--card); color: var(--ink); border: 1.5px solid var(--line); border-radius: 12px;
}
.opt:hover:not(:disabled) { border-color: var(--accent); filter: none; }
.opt b {
  width: 28px; height: 28px; border-radius: 50%; display: grid; place-items: center;
  background: var(--bg); border: 1px solid var(--line); font-size: .85rem; color: var(--muted);
}
.opt[aria-checked=true] { border-color: var(--accent); background: var(--accent-soft); }
.opt[aria-checked=true] b { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }

#q-submit { position: sticky; bottom: 12px; z-index: 2; box-shadow: 0 0 0 6px var(--card); }
#q-submit:disabled { opacity: 1; background: var(--line); color: var(--muted); }

.score { font-size: 3rem; font-weight: 800; letter-spacing: -.02em; line-height: 1.1; }
.score span { font-size: 1.25rem; color: var(--muted); font-weight: 600; }

/* --- панель преподавателя --- */
.toolbar { display: flex; gap: 10px; flex-wrap: wrap; align-items: center; }
.toolbar .grow { flex: 1; }
.stats { display: grid; grid-template-columns: repeat(auto-fit, minmax(120px, 1fr)); gap: 10px; }
.stat { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 12px 14px; }
.stat b { display: block; font-size: 1.5rem; font-variant-numeric: tabular-nums; }
.stat span { color: var(--muted); font-size: .82rem; }

.tablebox { overflow-x: auto; margin: 0 -24px; padding: 0 24px; }
table { border-collapse: collapse; width: 100%; font-size: .9rem; }
th, td { text-align: left; padding: 10px 10px; border-bottom: 1px solid var(--line); vertical-align: middle; }
th { color: var(--muted); font-weight: 600; font-size: .78rem; text-transform: uppercase; letter-spacing: .04em; white-space: nowrap; }
td.num, th.num { text-align: right; font-variant-numeric: tabular-nums; }
td.actions { white-space: nowrap; text-align: right; }
td.actions button + button { margin-left: 6px; }
tr:last-child td { border-bottom: 0; }
.name { font-weight: 600; }
.dot { display: inline-block; width: 8px; height: 8px; border-radius: 50%; background: var(--line); margin-right: 6px; }
.dot.on { background: var(--ok); }

.badge { display: inline-block; padding: 2px 10px; border-radius: 999px; font-size: .78rem; font-weight: 600; white-space: nowrap; }
.badge.waiting { background: var(--warn-soft); color: var(--warn); }
.badge.allowed { background: var(--accent-soft); color: var(--accent); }
.badge.in_progress { background: var(--ok-soft); color: var(--ok); }
.badge.finished { background: var(--bg); color: var(--muted); border: 1px solid var(--line); }
.badge.failed { background: var(--bad-soft); color: var(--bad); }
.mono { font-family: ui-monospace, "Cascadia Mono", Consolas, monospace; font-variant-numeric: tabular-nums; }

dialog {
  border: 1px solid var(--line); border-radius: var(--radius); padding: 0; color: var(--ink);
  background: var(--card); width: min(860px, calc(100vw - 32px)); max-height: calc(100vh - 48px);
}
dialog::backdrop { background: rgba(10, 12, 24, .55); }
.dlg-head { display: flex; justify-content: space-between; gap: 12px; align-items: start; padding: 20px 24px; border-bottom: 1px solid var(--line); position: sticky; top: 0; background: var(--card); }
.dlg-body { padding: 8px 24px 24px; }
.rq { padding: 16px 0; border-bottom: 1px solid var(--line); }
.rq:last-child { border-bottom: 0; }
.rq h3 { font-size: 1rem; margin-bottom: 8px; }
.rq ol { margin: 0; padding-left: 22px; font-size: .9rem; }
.rq li { padding: 3px 6px; border-radius: 6px; }
.rq li.right { color: var(--ok); }
.rq li.picked { background: var(--bad-soft); }
.rq li.picked.right { background: var(--ok-soft); }
.rq .tag { font-size: .75rem; color: var(--muted); }

@media (max-width: 560px) {
  body.in-exam .top, body.in-exam .eyebrow { display: none; }
  body.in-exam .wrap { padding-top: 12px; }
  .card { padding: 18px; }
  .tablebox { margin: 0 -18px; padding: 0 18px; }
  .stem { font-size: 1.08rem; }
  .opt { padding: 12px; font-size: .95rem; }
}

/* --- личный кабинет --- */
.pagetitle { margin: 0 0 16px 2px; }
.examhead { display: flex; justify-content: space-between; align-items: start; gap: 12px; }
.examhead h2 { margin-bottom: 4px; }
.result { font-size: 1.05rem; }
.result b { font-size: 1.25rem; }
.badge.none { background: var(--bg); color: var(--muted); border: 1px solid var(--line); }
.badge.requested { background: var(--warn-soft); color: var(--warn); }
tr.attention td { background: var(--warn-soft); }