:root {
  --bg: #fafaf9;
  --surface: #ffffff;
  --text: #1c1917;
  --muted: #78716c;
  --border: #e7e5e4;
  --accent: #2563eb;
  --accent-text: #ffffff;
  --ok: #15803d;
  --ok-bg: #dcfce7;
  --danger: #b91c1c;
  --lecture: #1d4ed8;
  --lecture-bg: #dbeafe;
  --task: #a16207;
  --task-bg: #fef3c7;
  --both: #7e22ce;
  --both-bg: #f3e8ff;
  --radius: 10px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0c0a09;
    --surface: #1c1917;
    --text: #f5f5f4;
    --muted: #a8a29e;
    --border: #2e2a27;
    --accent: #60a5fa;
    --accent-text: #0c0a09;
    --ok: #4ade80;
    --ok-bg: #14532d;
    --danger: #f87171;
    --lecture: #93c5fd;
    --lecture-bg: #1e3a8a;
    --task: #fcd34d;
    --task-bg: #713f12;
    --both: #d8b4fe;
    --both-bg: #581c87;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.55 system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  -webkit-text-size-adjust: 100%;
}

a { color: var(--accent); }

.wrap { max-width: 720px; margin: 0 auto; padding: 16px 16px 64px; }

/* header */
.top {
  position: sticky; top: 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between;
  max-width: 720px; margin: 0 auto; padding: 12px 16px;
  background: var(--bg); border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; letter-spacing: .08em; text-decoration: none; color: var(--text); }
.top-right { display: flex; align-items: center; gap: 12px; }
.points { font-weight: 600; font-variant-numeric: tabular-nums; }

/* generic */
h1 { font-size: 1.5rem; line-height: 1.25; margin: 8px 0 4px; }
h2 { font-size: 1.1rem; margin: 28px 0 8px; }
.muted { color: var(--muted); }
.small { font-size: .875rem; }
.back { display: inline-block; margin: 4px 0 8px; text-decoration: none; font-size: .9rem; }
.error { color: var(--danger); }
.empty { color: var(--muted); padding: 24px 0; }

.card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 16px;
}

/* lists */
.list { list-style: none; margin: 16px 0 0; padding: 0; display: grid; grid-template-columns: minmax(0, 1fr); gap: 10px; }
.list a.row {
  display: flex; align-items: center; gap: 12px;
  padding: 14px 16px; text-decoration: none; color: var(--text);
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius);
}
.list a.row:hover { border-color: var(--accent); }
.row .grow { flex: 1; min-width: 0; }
.row .title { font-weight: 600; }
.row .sub { color: var(--muted); font-size: .875rem; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.num {
  flex: none; width: 2rem; text-align: right; color: var(--muted);
  font-variant-numeric: tabular-nums;
}
.row.done .num { color: var(--ok); }

.progress { flex: none; text-align: right; font-variant-numeric: tabular-nums; font-size: .9rem; }
.bar { height: 4px; width: 72px; background: var(--border); border-radius: 2px; margin-top: 4px; overflow: hidden; }
.bar > span { display: block; height: 100%; background: var(--ok); }

.marks { flex: none; display: flex; gap: 4px; }
.mark {
  font-size: .75rem; padding: 2px 6px; border-radius: 999px;
  border: 1px solid var(--border); color: var(--muted);
}
.mark.on { background: var(--ok-bg); color: var(--ok); border-color: transparent; }

.badge {
  display: inline-block; font-size: .75rem; font-weight: 600; text-transform: uppercase;
  letter-spacing: .04em; padding: 2px 8px; border-radius: 999px;
}
.badge.lecture { background: var(--lecture-bg); color: var(--lecture); }
.badge.task { background: var(--task-bg); color: var(--task); }
.badge.both { background: var(--both-bg); color: var(--both); }

/* lesson */
.brief { font-size: 1.05rem; color: var(--muted); margin: 4px 0 0; }
.md { overflow-wrap: anywhere; }
.md img, .md video, .md iframe { max-width: 100%; height: auto; }
.md pre { overflow-x: auto; background: var(--surface); border: 1px solid var(--border); border-radius: 8px; padding: 12px; }
.md code { font-size: .9em; }
.md blockquote { margin: 0; padding-left: 12px; border-left: 3px solid var(--border); color: var(--muted); }
.links { padding-left: 20px; }
.links li { margin: 4px 0; overflow-wrap: anywhere; }

.done-line { color: var(--ok); font-weight: 600; }
.section { margin-top: 28px; }
.actions { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; margin-top: 12px; }

/* forms */
label { display: block; font-size: .875rem; font-weight: 600; margin: 12px 0 4px; }
input[type=email], input[type=password], input[type=url], textarea {
  width: 100%; font: inherit; color: var(--text); background: var(--bg);
  border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px;
}
input[type=file] { font: inherit; color: var(--text); max-width: 100%; }
textarea { min-height: 80px; resize: vertical; }
input:focus, textarea:focus { outline: 2px solid var(--accent); outline-offset: 0; border-color: transparent; }

button, .btn {
  font: inherit; font-weight: 600; cursor: pointer;
  padding: 10px 16px; border-radius: 8px; border: 1px solid transparent;
  background: var(--accent); color: var(--accent-text);
}
button.ghost { background: transparent; color: var(--text); border-color: var(--border); }
button.link { background: none; border: none; padding: 4px; color: var(--muted); font-weight: 500; text-decoration: underline; }
button.danger { color: var(--danger); }
button:disabled { opacity: .55; cursor: default; }

.login { max-width: 360px; margin: 48px auto 0; }
.login button { width: 100%; margin-top: 16px; }

.submission dl { display: grid; grid-template-columns: auto 1fr; gap: 4px 12px; margin: 8px 0 0; }
.submission dt { color: var(--muted); font-size: .875rem; }
.submission dd { margin: 0; overflow-wrap: anywhere; }