:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --surface-2: #f0f2f5;
  --border: #dde1e7;
  --text: #1b1f24;
  --muted: #5d6673;
  --accent: #2f5bd3;
  --accent-ink: #ffffff;
  --ok: #1d7a46;
  --ok-bg: #e5f4ea;
  --bad: #b42318;
  --bad-bg: #fdecea;
  --warn: #8a5a00;
  --warn-bg: #fff4dc;
  --tool: #6a3fc1;
  --mono: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --radius: 10px;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1216;
    --surface: #171b21;
    --surface-2: #1f242c;
    --border: #2c333d;
    --text: #e6e9ee;
    --muted: #97a1ae;
    --accent: #7ea2ff;
    --accent-ink: #0f1216;
    --ok: #5fd08f;
    --ok-bg: #12291c;
    --bad: #ff8a80;
    --bad-bg: #2e1614;
    --warn: #f0c060;
    --warn-bg: #2b220f;
    --tool: #b99bff;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0; background: var(--bg); color: var(--text);
  font: 15px/1.5 system-ui, -apple-system, "Segoe UI", sans-serif;
  min-height: 100vh; display: flex; flex-direction: column;
}
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
code, pre, textarea.code { font-family: var(--mono); font-size: 13px; }
h1 { font-size: 24px; margin: 0 0 4px; }
h2 { font-size: 17px; margin: 0 0 12px; }
h3 { font-size: 14px; margin: 0 0 8px; text-transform: uppercase; letter-spacing: .04em; color: var(--muted); }
.muted { color: var(--muted); }
.center { text-align: center; }
[hidden] { display: none !important; }

/* top bar */
.topbar {
  display: flex; align-items: center; gap: 24px; padding: 12px 24px;
  background: var(--surface); border-bottom: 1px solid var(--border);
  position: sticky; top: 0; z-index: 5;
}
.brand { font-weight: 700; color: var(--text); display: flex; align-items: center; gap: 8px; }
.brand:hover { text-decoration: none; }
.brand-mark {
  font-family: var(--mono); background: var(--accent); color: var(--accent-ink);
  padding: 1px 6px; border-radius: 6px; font-size: 13px;
}
nav { display: flex; gap: 4px; flex: 1; }
nav a { color: var(--muted); padding: 6px 10px; border-radius: 8px; }
nav a:hover { text-decoration: none; background: var(--surface-2); }
nav a.active { color: var(--text); background: var(--surface-2); font-weight: 600; }
.who { display: flex; gap: 12px; align-items: center; color: var(--muted); font-size: 14px; }

main { width: 100%; max-width: 1180px; margin: 0 auto; padding: 28px 24px 48px; flex: 1; }
.foot { text-align: center; color: var(--muted); font-size: 12px; padding: 16px; }

/* generic bits */
.panel { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; }
.stack > * + * { margin-top: 16px; }
button, .btn {
  font: inherit; border: 1px solid var(--border); background: var(--surface-2); color: var(--text);
  padding: 8px 14px; border-radius: 8px; cursor: pointer;
}
button.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); font-weight: 600; }
button:disabled { opacity: .55; cursor: not-allowed; }
button.link { background: none; border: 0; padding: 0; color: var(--accent); }
input, select, textarea {
  font: inherit; color: var(--text); background: var(--surface); border: 1px solid var(--border);
  border-radius: 8px; padding: 8px 10px; width: 100%;
}
input:focus, select:focus, textarea:focus { outline: 2px solid var(--accent); outline-offset: -1px; }
label { display: block; font-size: 13px; font-weight: 600; margin-bottom: 4px; }
.error-text { color: var(--bad); font-size: 14px; min-height: 1.5em; }
.pill {
  display: inline-block; font-size: 12px; padding: 2px 8px; border-radius: 999px;
  background: var(--surface-2); color: var(--muted); border: 1px solid var(--border); white-space: nowrap;
}
.pill.ok { background: var(--ok-bg); color: var(--ok); border-color: transparent; }
.pill.bad { background: var(--bad-bg); color: var(--bad); border-color: transparent; }
.pill.warn { background: var(--warn-bg); color: var(--warn); border-color: transparent; }

/* auth */
.auth { max-width: 400px; margin: 40px auto; }
.auth .tabs { display: flex; gap: 4px; margin-bottom: 18px; }
.auth .tabs button { flex: 1; }
.auth .tabs button.on { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); }
.auth form > div { margin-bottom: 12px; }

/* challenge list */
.page-head { display: flex; justify-content: space-between; align-items: end; gap: 16px; margin-bottom: 20px; flex-wrap: wrap; }
.grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 16px; }
.card {
  display: flex; flex-direction: column; gap: 10px; color: var(--text);
  background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px;
  transition: border-color .12s, transform .12s;
}
.card:hover { text-decoration: none; border-color: var(--accent); transform: translateY(-1px); }
.card.solved { border-left: 4px solid var(--ok); }
.card .num { font-family: var(--mono); color: var(--muted); font-size: 13px; }
.card .title { font-size: 17px; font-weight: 650; }
.card dl { margin: 0; font-size: 14px; display: grid; grid-template-columns: auto 1fr; gap: 4px 10px; }
.card dt { color: var(--muted); }
.card dd { margin: 0; }
.card .meta { display: flex; gap: 6px; flex-wrap: wrap; margin-top: auto; align-items: center; }
.card .meta .spacer { flex: 1; }

/* challenge page */
.crumb { font-size: 14px; margin-bottom: 8px; display: inline-block; }
.chal-layout { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 7fr); gap: 20px; align-items: start; }
@media (max-width: 900px) { .chal-layout { grid-template-columns: 1fr; } }
.briefing {
  white-space: pre-wrap; background: var(--surface-2); border-radius: 8px; padding: 14px;
  font-family: var(--mono); font-size: 13px; margin: 0; overflow-x: auto;
}
.scenario p { margin: 0 0 10px; }
.flagbox {
  font-family: var(--mono); background: var(--ok-bg); color: var(--ok); padding: 10px 12px;
  border-radius: 8px; display: flex; justify-content: space-between; gap: 10px; align-items: center;
  word-break: break-all;
}
textarea.code { min-height: 170px; resize: vertical; line-height: 1.45; }
.input-foot { display: flex; gap: 10px; align-items: center; margin-top: 10px; flex-wrap: wrap; }
.input-foot select { width: auto; }
.input-foot .count { margin-left: auto; font-size: 13px; color: var(--muted); font-family: var(--mono); }
.input-foot .count.over { color: var(--bad); font-weight: 700; }

/* result */
.verdict { border-radius: 8px; padding: 14px 16px; font-weight: 600; }
.verdict.ok { background: var(--ok-bg); color: var(--ok); }
.verdict.bad { background: var(--bad-bg); color: var(--bad); }
.verdict.warn { background: var(--warn-bg); color: var(--warn); }
.verdict .sub { font-weight: 400; font-size: 14px; margin-top: 4px; }
.running { display: flex; align-items: center; gap: 12px; padding: 18px; }
.spinner {
  width: 18px; height: 18px; border-radius: 50%; border: 2px solid var(--border);
  border-top-color: var(--accent); animation: spin .8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

.trace { list-style: none; padding: 0; margin: 0; position: relative; }
.trace::before { content: ""; position: absolute; left: 11px; top: 6px; bottom: 6px; width: 2px; background: var(--border); }
.trace li { position: relative; padding-left: 32px; margin-bottom: 12px; }
.trace li::before {
  content: ""; position: absolute; left: 6px; top: 6px; width: 12px; height: 12px; border-radius: 50%;
  background: var(--surface); border: 2px solid var(--muted);
}
.trace li.call::before { border-color: var(--tool); background: var(--tool); }
.trace li.agent::before { border-color: var(--accent); }
.trace .call-line { font-family: var(--mono); font-size: 13px; word-break: break-word; }
.trace .call-line .fn { color: var(--tool); font-weight: 700; }
.trace .call-line .args { color: var(--muted); }
.trace details { margin-top: 4px; }
.trace summary { cursor: pointer; font-size: 13px; color: var(--muted); }
.trace pre {
  white-space: pre-wrap; word-break: break-word; background: var(--surface-2); padding: 10px;
  border-radius: 8px; margin: 6px 0 0; max-height: 320px; overflow: auto;
}
.trace pre.err { color: var(--bad); }
.trace .agent-text { white-space: pre-wrap; background: var(--surface-2); padding: 10px 12px; border-radius: 8px; font-size: 14px; }
.kv { display: grid; grid-template-columns: auto 1fr; gap: 6px 14px; font-size: 14px; }
.kv dt { color: var(--muted); }
.kv dd { margin: 0; }

/* tables */
table { width: 100%; border-collapse: collapse; font-size: 14px; }
th, td { text-align: left; padding: 8px 10px; border-bottom: 1px solid var(--border); vertical-align: top; }
th { color: var(--muted); font-weight: 600; font-size: 12px; text-transform: uppercase; letter-spacing: .04em; }
tr.clickable { cursor: pointer; }
tr.clickable:hover td { background: var(--surface-2); }
tr.current td { background: var(--surface-2); }
td.mono, .mono { font-family: var(--mono); font-size: 13px; }
.preview { max-width: 380px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.table-wrap { overflow-x: auto; }
.filters { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 14px; }
.filters > * { width: auto; }
.stat-row { display: flex; gap: 12px; flex-wrap: wrap; margin-bottom: 16px; }
.stat { background: var(--surface); border: 1px solid var(--border); border-radius: var(--radius); padding: 12px 16px; min-width: 130px; }
.stat b { display: block; font-size: 22px; }
.stat span { color: var(--muted); font-size: 13px; }

@media (max-width: 640px) {
  .topbar { flex-wrap: wrap; gap: 10px; padding: 10px 16px; }
  nav { order: 3; flex-basis: 100%; }
  main { padding: 20px 16px 40px; }
}
.small { font-size: 13px; }
label.inline { margin: 0; font-weight: 400; }
.gap-below { margin-bottom: 16px; }