* { box-sizing: border-box; }
body { font-family: system-ui, "Segoe UI", Roboto, sans-serif; margin: 0;
  color: #1c2430; background: #f6f7f9; }
nav { display: flex; gap: 16px; align-items: center; padding: 10px 20px;
  background: #10233b; color: #fff; }
nav a { color: #cfe3ff; text-decoration: none; }
nav a.brand { font-weight: 700; color: #fff; font-size: 18px; }
nav .spacer { flex: 1; }
nav .who { opacity: .85; }
main { max-width: 900px; margin: 24px auto; padding: 0 16px; }
footer { text-align: center; color: #8a93a0; padding: 20px; font-size: 13px; }
table { width: 100%; border-collapse: collapse; background: #fff; }
th, td { padding: 8px 10px; border-bottom: 1px solid #e5e9ef; text-align: left; }
.flash { background: #e7f7ed; border: 1px solid #b7e4c7; padding: 8px 12px;
  border-radius: 6px; margin-bottom: 12px; }
.error { background: #fdecea; border: 1px solid #f5c6cb; padding: 8px 12px;
  border-radius: 6px; margin-bottom: 12px; color: #86281d; }
.stack { display: flex; flex-direction: column; gap: 12px; max-width: 380px; }
.stack label { display: flex; flex-direction: column; gap: 4px; font-size: 14px; }
input, select, textarea { padding: 8px; border: 1px solid #cfd6df;
  border-radius: 6px; font: inherit; }
textarea.code { font-family: Consolas, monospace; min-height: 260px; white-space: pre; }
button { padding: 8px 14px; border: 0; border-radius: 6px; cursor: pointer;
  background: #2563eb; color: #fff; }
form.inline { display: inline; }
.statement { background: #fff; padding: 18px 22px; border-radius: 8px;
  line-height: 1.55; }
.muted { color: #8a93a0; }
.badge { display: inline-block; padding: 2px 8px; border-radius: 999px;
  font-size: 12px; background: #e8edf3; }

/* ── Metrics panel (admin) ─────────────────────────────────────── */
.metrics-row { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 12px; margin-bottom: 22px; }
.metric-card { background: #fff; border: 1px solid #e5e9ef; border-radius: 10px;
  padding: 12px 14px; }
.metric-card.status.warn { border-color: #f5c6cb; background: #fff7f6; }
.metric-card.status.ok { border-color: #b7e4c7; background: #f4fbf6; }
.metric-label { font-size: 12px; text-transform: uppercase; letter-spacing: .06em;
  color: #8a93a0; }
.metric-value { font-size: 26px; font-weight: 700; margin: 2px 0 6px; }
.metric-card.status.warn .metric-value { color: #c0392b; }
.metric-card.status.ok .metric-value { color: #1e7e46; }
.metric-bar { height: 6px; border-radius: 999px; background: #edf0f4;
  overflow: hidden; margin-bottom: 6px; }
.metric-bar .fill { height: 100%; width: 0; background: #2563eb;
  border-radius: 999px; transition: width .5s ease; }
.metric-card.status.warn .fill { background: #c0392b; }
.metric-sub { font-size: 12px; }
.badge.accepted { background: #d9f4e2; color: #116631; }
.badge.wrong_answer { background: #fde3e1; color: #94241c; }
.badge.tle { background: #fff3cd; color: #7a5b00; }
.badge.compile_error, .badge.re, .badge.mle { background: #ffe1d6; color: #7c3208; }
pre.sample { background: #101828; color: #e6eaf2; padding: 10px;
  border-radius: 6px; overflow-x: auto; }