:root {
  --bg: #08080b;
  --bg-soft: #101017;
  --panel: #14141c;
  --panel-2: #1b1b25;
  --border: #2a2a36;
  --text: #e9e9ee;
  --muted: #9a9aa6;
  --brand: #c9a86a;
  --brand-soft: rgba(201, 168, 106, 0.14);
  --danger: #ff6f6f;
  --good: #86e898;
  --radius: 12px;
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  background:
    radial-gradient(1100px 520px at 50% -10%, rgba(201, 168, 106, 0.10), transparent 70%),
    var(--bg);
  color: var(--text);
  font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, sans-serif;
  line-height: 1.65;
  min-height: 100vh;
}

a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap { width: min(1080px, 100% - 32px); margin: 0 auto; }

.topbar {
  border-bottom: 1px solid var(--border);
  background: rgba(8, 8, 11, 0.86);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 20;
}
.topbar .wrap { display: flex; align-items: center; justify-content: space-between; height: 56px; }
.brand { display: flex; align-items: center; gap: 10px; font-size: 14px; letter-spacing: 0.4px; color: var(--muted); }
.brand .dot { width: 8px; height: 8px; border-radius: 50%; background: var(--brand); box-shadow: 0 0 12px var(--brand); }
.topbar .sub { font-size: 13px; color: var(--muted); }

main { padding: 28px 0 44px; }

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 20px;
  align-items: stretch;
  margin-bottom: 22px;
}

.hero-main {
  background: linear-gradient(180deg, var(--panel-2), var(--panel));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 26px 22px;
}
.kicker { margin: 0 0 8px; font-size: 12px; letter-spacing: 2px; color: var(--brand); }
.hero-main h1 { margin: 0 0 10px; font-size: 34px; letter-spacing: 2px; font-family: "SimSun", "Songti SC", serif; }
.lede { margin: 0 0 20px; color: var(--muted); max-width: 46ch; }

.start-row { display: flex; gap: 10px; flex-wrap: wrap; }
input[type="text"], input[type="password"], textarea {
  background: #0c0c12;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 12px;
  font: inherit;
  min-width: 0;
  flex: 1 1 220px;
}
input:focus, textarea:focus { outline: none; border-color: var(--brand); box-shadow: 0 0 0 3px var(--brand-soft); }

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: var(--panel-2);
  color: var(--text);
  border-radius: 10px;
  padding: 10px 16px;
  font: inherit;
  cursor: pointer;
  white-space: nowrap;
}
.btn:hover { border-color: var(--brand); text-decoration: none; }
.btn.primary { background: var(--brand); border-color: var(--brand); color: #1a1408; font-weight: 600; }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; }
.btn.danger { color: var(--danger); border-color: rgba(255, 111, 111, 0.4); }
.btn.small { padding: 5px 10px; font-size: 13px; border-radius: 8px; }
.btn[disabled] { opacity: 0.5; cursor: not-allowed; }

.hint { margin: 14px 0 0; font-size: 13px; color: var(--muted); }

.stats {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  display: grid;
  gap: 14px;
  align-content: start;
}
.stat { display: flex; align-items: baseline; justify-content: space-between; gap: 12px; }
.stat b { font-size: 22px; font-family: "DIN Alternate", Menlo, Consolas, monospace; color: var(--brand); }
.stat span { font-size: 13px; color: var(--muted); }

.grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 20px; }
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
}
.card h2 { margin: 0 0 4px; font-size: 17px; }
.card .card-sub { margin: 0 0 14px; font-size: 13px; color: var(--muted); }
.card.wide { grid-column: 1 / -1; }

table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 6px; border-bottom: 1px solid var(--border); }
th { color: var(--muted); font-weight: 500; font-size: 12px; letter-spacing: 1px; }
tbody tr:last-child td { border-bottom: none; }
td.rank { width: 44px; color: var(--brand); font-family: Menlo, Consolas, monospace; }
td.num { text-align: right; font-family: Menlo, Consolas, monospace; white-space: nowrap; }
.empty { color: var(--muted); font-size: 14px; padding: 10px 0; }

.hints { display: grid; gap: 8px; }
.hint-item {
  border: 1px dashed var(--border);
  border-radius: 10px;
  padding: 10px 12px;
  font-size: 14px;
  color: var(--muted);
  background: #0d0d13;
}
.hint-item.open { border-style: solid; border-color: var(--brand-soft); color: var(--text); }
.hint-item .idx { color: var(--brand); font-family: Menlo, Consolas, monospace; margin-right: 6px; }

.msg-form { display: flex; gap: 8px; margin-bottom: 14px; flex-wrap: wrap; }
.msg-form input { flex: 2 1 240px; }
.messages { display: grid; gap: 10px; max-height: 360px; overflow: auto; padding-right: 4px; }
.message { background: #0d0d13; border: 1px solid var(--border); border-radius: 10px; padding: 10px 12px; }
.message .meta { display: flex; justify-content: space-between; gap: 10px; font-size: 12px; color: var(--muted); margin-bottom: 4px; }
.message .body { font-size: 14px; word-break: break-word; }

.teacher-panel { display: none; }
.teacher-panel.show { display: block; }
.toolbar { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 12px; }
.notice { font-size: 13px; padding: 8px 10px; border-radius: 8px; background: var(--brand-soft); color: var(--brand); display: none; }
.notice.show { display: block; }
.notice.error { background: rgba(255, 111, 111, 0.12); color: var(--danger); }

footer { border-top: 1px solid var(--border); padding: 18px 0 34px; color: var(--muted); font-size: 13px; }
footer .wrap { display: flex; justify-content: space-between; gap: 12px; flex-wrap: wrap; }

@media (max-width: 880px) {
  .hero { grid-template-columns: minmax(0, 1fr); }
  .grid { grid-template-columns: minmax(0, 1fr); }
  .hero-main h1 { font-size: 26px; }
}