:root {
  --bg: #0c0e12;
  --panel: #12151c;
  --panel2: #171b24;
  --line: #232936;
  --text: #e8ecf3;
  --dim: #8b94a5;
  --accent: #4ade80;
  --accent2: #38bdf8;
  --danger: #f87171;
  --gold: #fbbf24;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  background: var(--bg); color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  line-height: 1.55;
}
code, pre, .mono { font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }
a { color: var(--accent2); text-decoration: none; }
.top {
  display: flex; justify-content: space-between; align-items: center;
  padding: 16px 28px; border-bottom: 1px solid var(--line);
  position: sticky; top: 0; background: rgba(12,14,18,.92); backdrop-filter: blur(6px); z-index: 5;
}
.brand { font-weight: 800; letter-spacing: .12em; font-size: 15px; }
.brand span { color: var(--accent); }
.top nav a { margin-left: 20px; color: var(--dim); font-size: 14px; }
.top nav a:hover { color: var(--text); }
.hero { padding: 84px 28px 56px; max-width: 980px; margin: 0 auto; text-align: center; }
.hero h1 { font-size: 52px; letter-spacing: -0.02em; margin-bottom: 18px; }
.lede { color: var(--dim); font-size: 18px; max-width: 720px; margin: 0 auto 28px; }
.hero-cta { display: flex; gap: 12px; justify-content: center; margin-bottom: 40px; }
.btn {
  display: inline-block; padding: 10px 18px; border-radius: 8px; border: 1px solid var(--line);
  background: var(--panel2); color: var(--text); font-size: 14px; cursor: pointer;
}
.btn:hover { border-color: var(--dim); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #06210f; font-weight: 700; }
.btn.danger { border-color: var(--danger); color: var(--danger); }
.btn.wide { width: 100%; margin-top: 8px; }
.btn:disabled { opacity: .35; cursor: not-allowed; }
.hero-stats { display: flex; gap: 36px; justify-content: center; }
.hero-stats div { display: flex; flex-direction: column; }
.hero-stats b { font-size: 22px; color: var(--accent); }
.hero-stats span { color: var(--dim); font-size: 12px; }
.panel { max-width: 980px; margin: 0 auto; padding: 48px 28px; border-top: 1px solid var(--line); }
.panel h2 { font-size: 28px; margin-bottom: 8px; }
.sub { color: var(--dim); margin-bottom: 22px; font-size: 14.5px; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(270px, 1fr)); gap: 16px; }
.card {
  background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 20px;
}
.card h3 { font-size: 17px; margin-bottom: 6px; }
.card .mode { display: inline-block; font-size: 11px; padding: 2px 8px; border-radius: 20px; border: 1px solid var(--accent2); color: var(--accent2); margin-bottom: 10px; }
.card .mode.adv { border-color: var(--gold); color: var(--gold); }
.card p { color: var(--dim); font-size: 13.5px; margin-bottom: 10px; }
.card .rubric { font-size: 12px; color: var(--dim); border-top: 1px solid var(--line); padding-top: 10px; }
.card .rubric b { color: var(--text); }
.room { display: grid; grid-template-columns: 280px 1fr; gap: 16px; }
.room-side { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 16px; }
.lbl { display: block; font-size: 12px; color: var(--dim); margin: 10px 0 4px; }
select, input[type=text] {
  width: 100%; background: var(--panel2); border: 1px solid var(--line); color: var(--text);
  border-radius: 8px; padding: 9px 10px; font-size: 14px;
}
.run-meta { font-size: 12px; margin-top: 12px; word-break: break-all; }
.side-actions { margin-top: 14px; border-top: 1px solid var(--line); padding-top: 8px; }
.audit-mini { margin-top: 16px; border-top: 1px solid var(--line); padding-top: 12px; }
.audit-mini h3 { font-size: 13px; margin-bottom: 8px; color: var(--dim); }
.chain { font-family: ui-monospace, Menlo, monospace; font-size: 10.5px; color: var(--dim); max-height: 220px; overflow-y: auto; }
.chain .entry { padding: 3px 0; border-bottom: 1px dashed var(--line); word-break: break-all; }
.chain .hash { color: var(--accent); }
.room-main { background: var(--panel); border: 1px solid var(--line); border-radius: 12px; padding: 16px; display: flex; flex-direction: column; }
.chat { flex: 1; min-height: 340px; max-height: 460px; overflow-y: auto; display: flex; flex-direction: column; gap: 10px; padding: 6px; }
.msg { max-width: 82%; padding: 10px 14px; border-radius: 12px; font-size: 14px; }
.msg.opp { background: var(--panel2); border: 1px solid var(--line); align-self: flex-start; }
.msg.me { background: #143324; border: 1px solid #1e5238; align-self: flex-end; }
.msg .who { display: block; font-size: 11px; color: var(--dim); margin-bottom: 3px; }
.composer { display: flex; gap: 8px; margin-top: 12px; }
.composer input { flex: 1; }
.center { text-align: center; margin: auto; }
.dim { color: var(--dim); }
.hidden { display: none; }
.result { margin-top: 16px; border: 1px solid var(--line); border-radius: 12px; padding: 18px; background: var(--panel2); }
.result h3 { margin-bottom: 10px; }
.grade { font-size: 44px; font-weight: 800; color: var(--accent); }
.grade.b { color: var(--accent2); } .grade.c { color: var(--gold); } .grade.f { color: var(--danger); }
.bars { margin: 14px 0; }
.bar-row { display: grid; grid-template-columns: 130px 1fr 44px; gap: 10px; align-items: center; margin: 5px 0; font-size: 12.5px; }
.bar-track { background: var(--bg); border-radius: 5px; height: 9px; overflow: hidden; }
.bar-fill { background: var(--accent2); height: 100%; }
.tips { font-size: 13.5px; color: var(--dim); }
.tips li { margin: 6px 0 6px 18px; }
.cert-box { margin-top: 12px; display: flex; gap: 8px; flex-wrap: wrap; }
.code {
  background: var(--panel); border: 1px solid var(--line); border-radius: 10px;
  padding: 18px; font-size: 13px; overflow-x: auto; color: #c7d0de;
}
.prog-table { width: 100%; border-collapse: collapse; font-size: 13px; margin-top: 10px; }
.prog-table th, .prog-table td { text-align: left; padding: 7px 10px; border-bottom: 1px solid var(--line); }
.prog-table th { color: var(--dim); font-weight: 600; font-size: 12px; }
.spark { display: flex; gap: 6px; align-items: flex-end; height: 60px; margin-top: 6px; }
.spark div { background: var(--accent2); width: 26px; border-radius: 3px 3px 0 0; position: relative; }
.spark span { position: absolute; top: -18px; left: 0; right: 0; text-align: center; font-size: 10px; color: var(--dim); }
footer {
  border-top: 1px solid var(--line); padding: 26px 28px; display: flex; justify-content: space-between;
  gap: 20px; flex-wrap: wrap; font-size: 12.5px; color: var(--dim); max-width: 980px; margin: 0 auto;
}
@media (max-width: 800px) {
  .room { grid-template-columns: 1fr; }
  .hero h1 { font-size: 36px; }
  .hero-stats { gap: 20px; flex-wrap: wrap; }
}