/* ProofDuel — tactical / arena aesthetic.
 * Dark background, monospace, red/amber accent, tier-coded hex chips.
 */

:root {
  --bg: #0a0a0a;
  --bg-elev: #131313;
  --bg-card: #181818;
  --line: #2a2a2a;
  --line-bright: #3a3a3a;
  --text: #e8e8e8;
  --text-dim: #8a8a8a;
  --text-faint: #525252;
  --accent: #ff6a00;
  --accent-soft: #ff6a0033;
  --accent-glow: #ff6a0099;
  --win: #57e389;
  --loss: #ff4a4a;
  --draw: #d4a017;
  --mono: 'JetBrains Mono', 'IBM Plex Mono', 'Fira Code', ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  --sans: ui-sans-serif, system-ui, -apple-system, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; background: var(--bg); color: var(--text); }
body {
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.5;
  min-height: 100vh;
  background:
    radial-gradient(ellipse at top, #1a0d04 0%, transparent 60%),
    radial-gradient(ellipse at bottom right, #0d1820 0%, transparent 50%),
    var(--bg);
  background-attachment: fixed;
}

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

.mono { font-family: var(--mono); }

/* ---- Layout ---- */
.container { max-width: 960px; margin: 0 auto; padding: 0 24px; }
.center { text-align: center; }
.stack > * + * { margin-top: 16px; }
.row { display: flex; gap: 16px; align-items: center; }

/* ---- Top nav ---- */
.nav {
  border-bottom: 1px solid var(--line);
  padding: 14px 0;
  background: rgba(10, 10, 10, 0.92);
  backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 10;
}
.nav-inner { display: flex; align-items: center; justify-content: space-between; }
.brand {
  font-family: var(--mono);
  font-weight: 800;
  letter-spacing: 0.04em;
  font-size: 18px;
  color: var(--text);
}
.brand .accent { color: var(--accent); }
.nav-links { display: flex; gap: 22px; }
.nav-links a { color: var(--text-dim); font-family: var(--mono); font-size: 13px; letter-spacing: 0.05em; text-transform: uppercase; }
.nav-links a:hover, .nav-links a.active { color: var(--text); text-decoration: none; }

/* ---- Hero (landing) ---- */
.hero { padding: 80px 0 60px; text-align: center; }
.hero h1 {
  font-family: var(--mono);
  font-size: clamp(40px, 8vw, 72px);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
  line-height: 1.05;
}
.hero h1 .accent { color: var(--accent); text-shadow: 0 0 24px var(--accent-glow); }
.hero p.tag { font-size: 18px; color: var(--text-dim); margin: 0 0 32px; font-family: var(--mono); }
.hero p.tag::before { content: "// "; color: var(--text-faint); }

/* ---- Buttons ---- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--mono);
  font-weight: 700;
  font-size: 15px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  padding: 14px 28px;
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #1a0f00;
  cursor: pointer;
  transition: all 0.15s ease;
  text-decoration: none;
}
.btn:hover { background: #ff8124; box-shadow: 0 0 0 4px var(--accent-soft); text-decoration: none; }
.btn:disabled { opacity: 0.4; cursor: not-allowed; }
.btn.ghost { background: transparent; color: var(--accent); }
.btn.ghost:hover { background: var(--accent-soft); }
.btn.muted { border-color: var(--line-bright); background: transparent; color: var(--text-dim); }
.btn.muted:hover { color: var(--text); border-color: var(--text-dim); background: transparent; }

/* ---- Card ---- */
.card {
  background: var(--bg-card);
  border: 1px solid var(--line);
  padding: 24px;
}
.card.tight { padding: 16px; }

/* ---- Tier chip ---- */
.tier-chip {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  padding: 4px 10px;
  border: 1px solid currentColor;
  border-radius: 0;
}
.tier-chip .dot { width: 8px; height: 8px; background: currentColor; }

/* ---- Fight card ---- */
.fight-card {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 32px;
  align-items: center;
  padding: 40px 24px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  margin: 24px 0;
}
.fight-side { text-align: center; }
.fight-side.left { animation: slideInL 0.5s ease-out; }
.fight-side.right { animation: slideInR 0.5s ease-out; }
.fight-side .handle {
  font-family: var(--mono);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: 0.04em;
}
.fight-side .rating {
  font-family: var(--mono);
  color: var(--text-dim);
  font-size: 14px;
  margin-top: 4px;
}
.fight-vs {
  font-family: var(--mono);
  font-weight: 900;
  font-size: 56px;
  color: var(--accent);
  text-shadow: 0 0 30px var(--accent-glow);
  animation: vsPulse 1.2s ease-in-out infinite;
}

@keyframes slideInL { from { opacity: 0; transform: translateX(-30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes slideInR { from { opacity: 0; transform: translateX(30px); } to { opacity: 1; transform: translateX(0); } }
@keyframes vsPulse { 0%,100% { transform: scale(1); } 50% { transform: scale(1.08); } }

/* ---- Problem display ---- */
.problem {
  font-size: 22px;
  line-height: 1.6;
  padding: 32px;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  margin: 24px 0;
}
.problem .meta {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin-bottom: 16px;
}

/* ---- Timer ---- */
.timer {
  font-family: var(--mono);
  font-size: 28px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--accent);
  text-align: right;
  font-variant-numeric: tabular-nums;
}

/* ---- Answer input ---- */
.answer-row {
  display: flex;
  gap: 12px;
  align-items: stretch;
  margin: 16px 0;
}
.answer-input {
  flex: 1;
  font-family: var(--mono);
  font-size: 20px;
  padding: 16px;
  background: var(--bg-elev);
  color: var(--text);
  border: 1px solid var(--line-bright);
  outline: none;
}
.answer-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

/* ---- Result screen ---- */
.result {
  text-align: center;
  padding: 40px 24px;
  border: 1px solid var(--line);
  margin: 24px 0;
}
.result h2 {
  font-family: var(--mono);
  font-size: 48px;
  margin: 0 0 8px;
  letter-spacing: -0.02em;
}
.result.win h2 { color: var(--win); }
.result.loss h2 { color: var(--loss); }
.result.draw h2 { color: var(--draw); }
.result .delta {
  font-family: var(--mono);
  font-size: 18px;
  color: var(--text-dim);
}
.result .delta .pos { color: var(--win); }
.result .delta .neg { color: var(--loss); }
.result .recap {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin: 24px auto;
  max-width: 480px;
  text-align: left;
}
.result .recap > div { background: var(--bg-elev); padding: 12px 16px; border: 1px solid var(--line); }
.result .recap .label { font-family: var(--mono); font-size: 11px; color: var(--text-faint); text-transform: uppercase; letter-spacing: 0.1em; }
.result .recap .value { font-family: var(--mono); font-size: 20px; margin-top: 4px; }
.result .solution {
  margin-top: 16px;
  text-align: left;
  background: var(--bg-elev);
  border: 1px solid var(--line);
  padding: 16px 20px;
  color: var(--text-dim);
  font-size: 14px;
}
.result .solution strong { color: var(--text); font-family: var(--mono); font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em; display: block; margin-bottom: 6px; }

/* ---- Leaderboard ---- */
.leader-table { width: 100%; border-collapse: collapse; margin-top: 16px; }
.leader-table th, .leader-table td {
  padding: 12px 16px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  font-family: var(--mono);
}
.leader-table th { font-size: 11px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--text-faint); }
.leader-table td.rank { color: var(--text-dim); width: 60px; }
.leader-table td.rating { font-weight: 700; text-align: right; }

/* ---- Loading ---- */
.spinner {
  display: inline-block;
  width: 16px; height: 16px;
  border: 2px solid var(--line-bright);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  vertical-align: middle;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ---- Footer ---- */
.footer {
  margin-top: 80px;
  padding: 32px 0;
  border-top: 1px solid var(--line);
  text-align: center;
  color: var(--text-faint);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.05em;
}

/* ---- Generic typography ---- */
h2 { font-family: var(--mono); letter-spacing: -0.01em; }
h3 { font-family: var(--mono); font-size: 16px; letter-spacing: 0.04em; color: var(--text-dim); text-transform: uppercase; }
code { font-family: var(--mono); background: var(--bg-elev); padding: 2px 6px; border: 1px solid var(--line); font-size: 0.9em; }

/* ---- Mobile ---- */
@media (max-width: 640px) {
  .container { padding: 0 16px; }
  .fight-card { grid-template-columns: 1fr; gap: 16px; padding: 24px 16px; }
  .fight-vs { font-size: 36px; }
  .nav-links { gap: 14px; }
  .nav-links a { font-size: 11px; }
  .answer-row { flex-direction: column; }
  .problem { font-size: 18px; padding: 20px; }
}