:root {
  --paper: #ffffff;
  --ink: #111827;
  --muted: #64748b;
  --line: #e2e8f0;
  --soft: #f8fafc;
  --accent: #27364a;
  --accent-soft: #f1f5f9;
  --warning: #b45309;
  --danger: #be123c;
  --challenge: #334155;
  --challenge-soft: #f1f5f9;
  --max: 1180px;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}
a { color: inherit; }
button, input { font: inherit; }
button { cursor: pointer; }
h1, h2, h3, h4, p { overflow-wrap: anywhere; }
.site-header {
  width: min(var(--max), calc(100% - 40px));
  min-height: 70px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  border-bottom: 1px solid var(--line);
}
.brand { display: inline-flex; align-items: center; gap: 9px; font-weight: 900; letter-spacing: -.04em; text-decoration: none; }
.brand img { width: 27px; height: 27px; border-radius: 7px; object-fit: cover; }
nav { display: flex; gap: 24px; }
nav a { color: var(--muted); font-size: .92rem; text-decoration: none; }
nav a:hover { color: var(--ink); }
main, footer, .page-status { width: min(var(--max), calc(100% - 40px)); margin: 0 auto; }

.hero { padding: 86px 0 52px; max-width: none; }
.hero-heading { display: grid; grid-template-columns: minmax(0, 1fr) 190px; gap: 54px; align-items: center; }
.tues-logo-lockup { margin: 0; }
.tues-logo-lockup img { display: block; width: 180px; aspect-ratio: 1; border-radius: 22px; object-fit: cover; filter: saturate(.78) contrast(.96); box-shadow: 0 10px 28px #0f172a1a; }
.tues-logo-lockup figcaption { margin-top: 8px; color: var(--muted); font-size: .7rem; font-weight: 850; letter-spacing: .12em; text-align: center; text-transform: uppercase; }
.eyebrow { margin: 0 0 12px; color: var(--challenge, var(--accent)); font-size: .74rem; font-weight: 900; letter-spacing: .12em; text-transform: uppercase; }
h1 { max-width: 840px; margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: clamp(3rem, 8vw, 6.7rem); font-weight: 500; letter-spacing: -.055em; line-height: .94; }
.hero-copy { max-width: 680px; margin: 28px 0 0; color: var(--muted); font-size: 1.12rem; }
.identity { max-width: 470px; margin-top: 36px; }
.identity label { display: block; margin-bottom: 7px; font-size: .82rem; font-weight: 800; }
.identity-row { display: flex; gap: 8px; }
.identity input { min-width: 0; flex: 1; border: 1px solid #cbd5e1; border-radius: 9px; padding: 11px 13px; color: var(--ink); background: #fff; box-shadow: 0 1px 2px #0f172a0a; }
.identity button, .copy-button { border: 0; border-radius: 8px; padding: 10px 15px; background: var(--ink); color: #fff; font-weight: 800; }
.hint { margin: 6px 0 0; color: var(--muted); font-size: .78rem; }
.status-strip, .page-status { min-height: 54px; display: flex; align-items: center; gap: 10px; padding: 13px 0; border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--muted); font-size: .9rem; }
.page-status { border-top: 0; }
.status-dot { width: 9px; height: 9px; border-radius: 50%; background: #94a3b8; box-shadow: 0 0 0 4px #f1f5f9; }
.status-dot.online { background: #10b981; box-shadow: 0 0 0 4px #d1fae5; }
.status-dot.offline { background: #f59e0b; box-shadow: 0 0 0 4px #fef3c7; }
.status-dot.error { background: #ef4444; box-shadow: 0 0 0 4px #fee2e2; }
.progress-summary { margin-left: auto; color: var(--ink); font-weight: 800; }

.challenge-section { padding: 76px 0 96px; }
.section-heading { display: grid; grid-template-columns: minmax(0, 1fr) minmax(280px, 480px); gap: 40px; align-items: end; }
.section-heading h2, .section-title h2 { margin: 0; font-family: Georgia, "Times New Roman", serif; font-size: clamp(2rem, 5vw, 3.8rem); font-weight: 500; letter-spacing: -.04em; line-height: 1; }
.section-heading > p, .section-title > p { margin: 0; color: var(--muted); }
.level { margin-top: 64px; }
.level-header { display: flex; align-items: baseline; justify-content: space-between; gap: 20px; margin-bottom: 16px; }
.level-header h3 { margin: 0; font-size: 1rem; letter-spacing: .08em; text-transform: uppercase; }
.level-rule { color: var(--muted); font-size: .86rem; }
.curriculum-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 14px; }
.level:first-child .curriculum-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.curriculum-card {
  position: relative; min-height: 260px; display: grid; grid-template-columns: 42px 1fr auto; grid-template-rows: auto 1fr auto; gap: 14px;
  overflow: hidden; padding: 24px; border: 1px solid var(--line); border-radius: 16px; background: #fff; text-decoration: none;
  box-shadow: 0 4px 14px #0f172a08; transition: transform .18s ease, box-shadow .18s ease, border-color .18s ease;
}
.curriculum-card:hover { transform: translateY(-3px); border-color: #94a3b8; box-shadow: 0 14px 30px #0f172a12; }
.curriculum-card.locked { opacity: .62; }
.card-accent { position: absolute; inset: 0 0 auto; height: 3px; background: var(--challenge); }
.card-number { color: var(--challenge); font: 700 1.3rem Georgia, serif; }
.card-copy { grid-column: 1 / 4; }
.card-modality { color: var(--muted); font-size: .7rem; font-weight: 900; letter-spacing: .08em; text-transform: uppercase; }
.card-copy h4 { margin: 7px 0 9px; font: 500 clamp(1.6rem, 3vw, 2.35rem)/1 Georgia, serif; letter-spacing: -.035em; }
.card-copy p { margin: 0; color: #334155; font-weight: 650; line-height: 1.35; }
.card-paper { display: block; margin-top: 14px; color: var(--muted); font-size: .76rem; }
.challenge-state { width: fit-content; color: var(--muted); font-size: .68rem; font-weight: 900; letter-spacing: .06em; text-transform: uppercase; }
.challenge-state.passed { color: #166534; }
.challenge-state.locked { color: var(--warning); }
.card-arrow { align-self: end; justify-self: end; color: #475569; font-size: 1.35rem; font-weight: 900; }

/* Standalone challenge pages */
.challenge-page main { --challenge: inherit; }
.challenge-hero { padding: 70px 0 48px; }
.challenge-hero-top { display: flex; align-items: center; gap: 10px; margin-bottom: 30px; }
.challenge-index { color: var(--challenge); font: 700 1.25rem Georgia, serif; }
.modality-pill, .metric-pill { color: var(--challenge); font-size: .72rem; font-weight: 850; letter-spacing: .04em; text-transform: uppercase; }
.challenge-hero h1 { color: var(--ink); font-size: clamp(3.6rem, 9vw, 7.7rem); }
.challenge-intro { max-width: 820px; margin: 25px 0 0; color: #334155; font-size: 1.2rem; }
.paper-spotlight { display: grid; grid-template-columns: minmax(0, 1.5fr) auto; gap: 30px; padding: 34px 0; border-block: 1px solid #cbd5e1; }
.colorful-paper { position: relative; }
.paper-label { color: var(--challenge); font-size: .72rem; font-weight: 900; letter-spacing: .1em; text-transform: uppercase; }
.paper-title { position: relative; z-index: 1; max-width: 820px; margin: 8px 0 10px; font-family: Georgia, "Times New Roman", serif; font-size: clamp(1.8rem, 4vw, 3.1rem); font-weight: 500; line-height: 1.08; letter-spacing: -.035em; }
.paper-authors { margin: 0; color: var(--muted); }
.paper-button { z-index: 1; align-self: end; border-radius: 10px; padding: 12px 17px; background: var(--ink); color: #fff; font-weight: 850; text-decoration: none; white-space: nowrap; }
.rules-layout { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; margin-top: 42px; }
.rule-panel { padding: 22px 0 0; border-top: 2px solid #475569; }
.rule-panel h2 { margin: 0 0 13px; color: var(--challenge); font-size: .82rem; letter-spacing: .1em; text-transform: uppercase; }
.rule-panel ul { margin: 0; padding-left: 20px; color: #475569; }
.rule-panel li + li { margin-top: 8px; }
.forbidden-panel { border-top-color: #9f1239; }
.forbidden-panel h2 { color: #881337; }
.code-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-top: 62px; }
.code-section { min-width: 0; }
.code-heading { min-height: 62px; display: flex; align-items: baseline; gap: 12px; }
.code-heading span { color: var(--challenge); font: 700 1rem Georgia, serif; }
.code-heading h2 { margin: 0; font: 500 1.5rem Georgia, serif; }
.code-frame { position: relative; overflow: hidden; border: 1px solid #1e293b; border-radius: 14px; background: #0f172a; box-shadow: 0 18px 38px #0f172a24; }
.code-frame pre { min-height: 430px; max-height: 560px; margin: 0; overflow: auto; padding: 25px; color: #dbeafe; font: 12.5px/1.65 ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; white-space: pre; tab-size: 4; }
.copy-button { position: absolute; z-index: 2; top: 10px; right: 10px; border: 1px solid #475569; padding: 6px 10px; background: #1e293b; color: #e2e8f0; font-size: .7rem; }
/* Prism Python palette */
.token.comment, .token.prolog, .token.doctype, .token.cdata { color: #7dd3fc; font-style: italic; }
.token.punctuation { color: #cbd5e1; }
.token.namespace { opacity: .8; }
.token.property, .token.tag, .token.constant, .token.symbol, .token.deleted { color: #fb7185; }
.token.boolean, .token.number { color: #fbbf24; }
.token.selector, .token.attr-name, .token.string, .token.char, .token.builtin, .token.inserted { color: #86efac; }
.token.operator, .token.entity, .token.url, .language-css .token.string, .style .token.string { color: #67e8f9; }
.token.atrule, .token.attr-value, .token.keyword { color: #c4b5fd; font-weight: 700; }
.token.function, .token.class-name { color: #f9a8d4; }
.token.regex, .token.important, .token.variable { color: #fdba74; }

.references, .leaderboard { margin-top: 78px; }
.section-title { display: grid; grid-template-columns: 1fr minmax(240px, 440px); gap: 28px; align-items: end; margin-bottom: 24px; }
.section-title h2 { font-size: clamp(2rem, 4vw, 3.2rem); }
.reference-list { display: grid; grid-template-columns: repeat(3, 1fr); border-block: 1px solid var(--line); }
.reference-item { min-height: 135px; display: flex; flex-direction: column; padding: 20px 24px; }
.reference-item + .reference-item { border-left: 1px solid var(--line); }
.reference-paper { --reference: #64748b; }
.reference-pass { --reference: var(--challenge); }
.reference-strong { --reference: #334155; }
.reference-kicker { color: var(--reference); font-size: .74rem; font-weight: 900; letter-spacing: .06em; text-transform: uppercase; }
.reference-item strong { margin-top: auto; font: 500 2.4rem Georgia, serif; }
.reference-item small { color: var(--muted); }
.metric-pill { justify-self: end; }
.scoreboard { border-top: 1px solid #94a3b8; }
.score-row { display: grid; grid-template-columns: 58px minmax(140px, 1fr) 120px 100px; gap: 16px; align-items: center; min-height: 58px; padding: 10px 4px; border-bottom: 1px solid var(--line); }
.score-row:hover { background: #fafafa; }
.score-row.rank-1, .score-row.rank-2, .score-row.rank-3 { font-size: 1.02rem; }
.rank-badge { color: #475569; font-weight: 900; text-align: center; }
.student-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.score-value { justify-self: end; font-variant-numeric: tabular-nums; }
.runs-cell { justify-self: end; color: var(--muted); font-size: .76rem; }
.run-history summary { color: var(--challenge); cursor: pointer; font-weight: 800; }
.run-row { display: flex; justify-content: space-between; gap: 12px; margin-top: 5px; white-space: nowrap; }
.empty-board { padding: 38px 0; border-block: 1px solid var(--line); color: var(--muted); text-align: center; }
.challenge-navigation { display: flex; justify-content: space-between; gap: 18px; margin: 72px 0 20px; padding-top: 24px; border-top: 1px solid var(--line); }
.challenge-navigation a { color: var(--challenge); font-weight: 800; text-decoration: none; }
footer { display: flex; justify-content: space-between; gap: 30px; padding: 28px 0 42px; margin-top: 70px; border-top: 1px solid var(--line); color: var(--muted); font-size: .82rem; }
footer p { margin: 0; }

@media (max-width: 900px) {
  .level:first-child .curriculum-grid, .curriculum-grid { grid-template-columns: 1fr 1fr; }
  .code-grid { grid-template-columns: 1fr; }
  .code-frame pre { min-height: 0; }
}
@media (max-width: 700px) {
  .site-header, main, footer, .page-status { width: min(100% - 28px, var(--max)); }
  nav a:first-child { display: none; }
  .hero { padding-top: 58px; }
  .hero-heading { grid-template-columns: 1fr; }
  .tues-logo-lockup { display: none; }
  .section-heading, .section-title, .paper-spotlight, .rules-layout { grid-template-columns: 1fr; }
  .level:first-child .curriculum-grid, .curriculum-grid { grid-template-columns: 1fr; }
  .reference-list { grid-template-columns: 1fr; }
  .reference-item + .reference-item { border-left: 0; border-top: 1px solid var(--line); }
  .paper-button, .metric-pill { justify-self: start; }
  .progress-summary { display: none; }
  .challenge-hero { padding-top: 48px; }
  .score-row { grid-template-columns: 38px minmax(0, 1fr) 86px; padding: 10px 0; }
  .runs-cell { display: none; }
  footer { flex-direction: column; }
}
@media (max-width: 480px) {
  .identity-row { flex-direction: column; }
  .curriculum-card { min-height: 235px; padding: 20px; }
  .challenge-hero-top { flex-wrap: wrap; }
  .paper-spotlight { padding: 24px 0; }
  .rule-panel { padding-top: 18px; }
  .code-frame { margin-inline: -7px; }
  .challenge-navigation { flex-direction: column; }
}