/* 2Dozen — dark, confident, no gradients. Geometric grotesk wordmark, mono numerals. */

:root {
  --bg: #0a0b0d;
  --bg-alt: #0e1012;
  --surface: #16181b;
  --surface-raised: #1e2124;
  --border: #2a2d31;
  --border-soft: #202226;
  --text: #f5f6f7;
  --text-dim: #9298a0;
  --text-faint: #5c6167;
  --accent: #c6ff5e;
  --accent-strong: #d8ff8a;
  --accent-ink: #0f1a04;
  --good: #6ee787;
  --bad: #ff6b5e;

  --font-display: 'Bricolage Grotesque', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'SFMono-Regular', Menlo, monospace;
  --font-sans: 'Bricolage Grotesque', system-ui, sans-serif;

  --radius: 18px;
  --radius-sm: 11px;
  --tile-size: 78px;

  color-scheme: dark;
}

* { box-sizing: border-box; }

[hidden] { display: none !important; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  min-height: 100%;
}

body {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding-bottom: 48px;
  position: relative;
}

.noise-overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  opacity: 0.045;
  mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

.storage-notice {
  width: 100%;
  background: var(--surface-raised);
  color: var(--text-dim);
  font-size: 12.5px;
  text-align: center;
  padding: 8px 16px;
  border-bottom: 1px solid var(--border);
  position: relative;
  z-index: 2;
}

/* ---------- header ---------- */

.app-header {
  width: 100%;
  max-width: 480px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 18px 10px;
  position: relative;
  z-index: 1;
}

.wordmark {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: 24px;
  letter-spacing: -0.03em;
  color: var(--text);
  font-optical-sizing: auto;
}

.wordmark-num {
  color: var(--accent);
}

.header-icons {
  display: flex;
  align-items: center;
  gap: 4px;
}

.icon-btn {
  background: none;
  border: none;
  color: var(--text-dim);
  padding: 8px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  gap: 4px;
  cursor: pointer;
  transition: background 0.15s, color 0.15s;
  -webkit-tap-highlight-color: transparent;
}

.icon-btn:hover, .icon-btn:focus-visible {
  background: var(--surface);
  color: var(--text);
}

.streak-btn { color: var(--text-dim); cursor: default; }
.streak-btn:hover, .streak-btn:focus-visible { background: none; color: var(--text-dim); }
.streak-btn.has-streak:hover { color: var(--accent); }
.streak-count {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  min-width: 8px;
}
.streak-btn.has-streak { color: var(--accent); }
.streak-btn.has-streak .streak-count { color: var(--accent-strong); }

/* ---------- main ---------- */

#app {
  width: 100%;
  max-width: 480px;
  padding: 8px 18px 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
  z-index: 1;
}

.practice-banner {
  width: 100%;
  margin-top: 14px;
  padding: 10px 14px;
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  font-size: 12.5px;
  color: var(--text-dim);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px 10px;
}

.practice-banner a, #practice-back {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px dashed var(--accent);
  font-weight: 600;
}

.results-solution {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--accent);
  margin-top: 8px;
  text-align: center;
}

.puzzle-meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 10px;
}

.puzzle-label {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--text-faint);
  letter-spacing: 0.02em;
}

.difficulty-badge {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.09em;
  padding: 3px 8px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-dim);
  text-transform: uppercase;
}

.difficulty-badge[data-diff="EASY"] { color: var(--good); border-color: color-mix(in srgb, var(--good) 40%, var(--border)); }
.difficulty-badge[data-diff="MEDIUM"] { color: var(--accent); border-color: color-mix(in srgb, var(--accent) 40%, var(--border)); }
.difficulty-badge[data-diff="HARD"] { color: var(--bad); border-color: color-mix(in srgb, var(--bad) 40%, var(--border)); }

.timer-row {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 6px;
  min-height: 34px;
}

.timer {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 600;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}

.practice-badge {
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-ink);
  background: var(--accent);
  padding: 3px 9px;
  border-radius: 999px;
}

.hint {
  margin-top: 14px;
  min-height: 20px;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 500;
  color: var(--text-dim);
  text-align: center;
}

.hint .hint-op {
  color: var(--accent);
  font-weight: 700;
}

.hint.hint-stuck {
  color: var(--bad);
}

/* ---------- board ---------- */

.board {
  width: 100%;
  margin-top: 22px;
  min-height: calc(var(--tile-size) + 8px);
  display: flex;
  align-items: center;
  justify-content: center;
}

.tiles {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: flex-start;
  gap: 12px 14px;
  perspective: 600px;
}

.tile-wrap {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: var(--tile-size);
}

.tile-derivation {
  margin-top: 7px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 500;
  color: var(--text-faint);
  text-align: center;
  line-height: 1.35;
  min-height: 1.35em;
  max-width: 108px;
  overflow-wrap: break-word;
}

.tile {
  width: var(--tile-size);
  height: var(--tile-size);
  border-radius: var(--radius);
  background: var(--surface);
  border: 1px solid var(--border-soft);
  display: flex;
  align-items: center;
  justify-content: center;
  font-family: var(--font-mono);
  font-weight: 600;
  font-size: 24px;
  color: var(--text);
  cursor: pointer;
  box-shadow: 0 1px 0 rgba(0,0,0,0.4), 0 8px 20px -12px rgba(0,0,0,0.7);
  transition: transform 0.12s ease, background 0.15s, border-color 0.15s, box-shadow 0.15s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
  position: relative;
}

.tile.frac {
  font-size: 16px;
  line-height: 1.15;
  flex-direction: column;
}
.tile.frac .frac-num { border-bottom: 1.5px solid currentColor; padding: 0 4px 1px; }
.tile.frac .frac-den { padding: 1px 4px 0; }
.tile.frac .frac-sign { margin-right: 2px; }

.tile:active { transform: scale(0.96); }

.tile.selected {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
  box-shadow: 0 0 0 3px color-mix(in srgb, var(--accent) 25%, transparent), 0 8px 20px -10px rgba(0,0,0,0.8);
}

.tile.newly-formed {
  animation: tile-pop 0.28s ease;
}

@keyframes tile-pop {
  0% { transform: scale(0.7); opacity: 0; }
  70% { transform: scale(1.08); opacity: 1; }
  100% { transform: scale(1); }
}

.tile.shake {
  animation: tile-shake 0.4s ease;
}

@keyframes tile-shake {
  0%, 100% { transform: translateX(0); }
  20% { transform: translateX(-7px); }
  40% { transform: translateX(6px); }
  60% { transform: translateX(-4px); }
  80% { transform: translateX(3px); }
}

.tile.solved-glow {
  border-color: var(--accent);
  color: var(--accent-strong);
}

.board.solving .tile {
  animation: converge 0.7s cubic-bezier(0.2, 0.8, 0.2, 1) forwards;
}

@keyframes converge {
  0% { transform: scale(1); }
  55% { transform: scale(1.25); }
  100% { transform: scale(1.15); }
}

@media (prefers-reduced-motion: reduce) {
  .tile.newly-formed, .tile.shake, .board.solving .tile {
    animation: none !important;
  }
  .tile { transition: none; }
}

/* ---------- operators & actions ---------- */

.controls {
  width: 100%;
  margin-top: 30px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 18px;
}

.operators {
  display: flex;
  gap: 12px;
}

.op-btn {
  width: 58px;
  height: 58px;
  border-radius: 50%;
  background: var(--surface);
  border: 1px solid var(--border-soft);
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s, transform 0.1s;
  -webkit-tap-highlight-color: transparent;
}

.op-btn:active { transform: scale(0.94); }

.op-btn.selected {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
}

.op-btn:disabled {
  opacity: 0.35;
  cursor: default;
}

.action-row {
  display: flex;
  gap: 10px;
  width: 100%;
  justify-content: center;
}

.action-btn {
  font-family: var(--font-sans);
  font-size: 14px;
  font-weight: 600;
  padding: 11px 18px;
  border-radius: 999px;
  background: var(--surface);
  border: 1px solid var(--border-soft);
  color: var(--text);
  cursor: pointer;
  transition: background 0.15s, opacity 0.15s;
  -webkit-tap-highlight-color: transparent;
}

.action-btn:hover:not(:disabled) { background: var(--surface-raised); }
.action-btn:disabled { opacity: 0.35; cursor: default; }

.action-btn-quiet {
  background: none;
  border-color: transparent;
  color: var(--text-faint);
}

.action-btn-primary {
  background: var(--accent);
  border-color: var(--accent);
  color: var(--accent-ink);
}
.action-btn-primary:hover { background: var(--accent-strong); }

/* ---------- results ---------- */

.results {
  width: 100%;
  margin-top: 28px;
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  animation: fade-in 0.4s ease;
}

@keyframes fade-in {
  from { opacity: 0; transform: translateY(6px); }
  to { opacity: 1; transform: translateY(0); }
}

.results-stars {
  font-size: 34px;
  letter-spacing: 6px;
  color: var(--border);
}
.results-stars .lit { color: var(--accent); }

.results-summary {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--text-dim);
  margin-top: 6px;
}

.share-wrap {
  position: relative;
  display: inline-flex;
  margin-top: 16px;
}

.share-btn {
  font-family: var(--font-sans);
  font-weight: 600;
  font-size: 14px;
  padding: 12px 24px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s;
}
.share-btn:active { transform: scale(0.97); }
.share-btn:hover { background: var(--accent-strong); }

.share-menu {
  position: absolute;
  top: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 6px;
  display: flex;
  flex-direction: column;
  min-width: 168px;
  box-shadow: 0 14px 34px -12px rgba(0,0,0,0.7);
  z-index: 10;
  animation: fade-in 0.15s ease;
}

.share-menu-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 9px 12px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 13.5px;
  font-weight: 500;
  color: var(--text);
  text-decoration: none;
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  width: 100%;
}
.share-menu-item:hover { background: var(--surface-raised); }
.share-menu-item svg { color: var(--text-dim); flex-shrink: 0; }

.countdown-row {
  margin-top: 22px;
  display: flex;
  gap: 8px;
  align-items: baseline;
  font-size: 13px;
  color: var(--text-faint);
}

.countdown {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}

.leaderboard-inline {
  width: 100%;
  margin-top: 26px;
  text-align: left;
}

.leaderboard-inline h3 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.01em;
  font-size: 17px;
  margin: 0 0 10px;
  color: var(--text);
}

.leaderboard-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--surface);
}

.leaderboard-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  font-size: 14px;
  border-bottom: 1px solid var(--border-soft);
}
.leaderboard-list li:last-child { border-bottom: none; }

.leaderboard-loading, .leaderboard-empty {
  color: var(--text-faint);
  font-style: italic;
  justify-content: center;
}

.leaderboard-locked {
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 22px 14px;
  text-align: center;
}
.leaderboard-locked span {
  color: var(--text-dim);
  font-size: 13.5px;
}

.leaderboard-cta-btn {
  font-family: var(--font-sans);
  font-weight: 700;
  font-size: 13px;
  padding: 9px 18px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-ink);
  border: none;
  cursor: pointer;
}
.leaderboard-cta-btn:hover { background: var(--accent-strong); }

.lb-rank {
  font-family: var(--font-mono);
  color: var(--text-faint);
  width: 24px;
  flex-shrink: 0;
}
.lb-handle {
  flex: 1;
  font-weight: 600;
  color: var(--text);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.lb-time {
  font-family: var(--font-mono);
  color: var(--text-dim);
  font-variant-numeric: tabular-nums;
}
.lb-stars { color: var(--accent); font-size: 12px; letter-spacing: 1px; }

.leaderboard-list li.is-you {
  background: color-mix(in srgb, var(--accent) 12%, var(--surface));
}
.leaderboard-list li.is-you .lb-handle { color: var(--accent-strong); }

.leaderboard-own-rank {
  margin-top: 8px;
  font-size: 13px;
  color: var(--text-faint);
}

.practice-link {
  margin-top: 30px;
  font-size: 14px;
  color: var(--text-dim);
  text-decoration: none;
  border-bottom: 1px dashed var(--text-faint);
  padding-bottom: 1px;
}
.practice-link:hover { color: var(--accent); border-color: var(--accent); }

/* ---------- modals ---------- */

.modal {
  border: none;
  padding: 0;
  background: transparent;
  color: var(--text);
  max-width: 420px;
  width: calc(100vw - 48px);
  border-radius: var(--radius);
}

.modal::backdrop {
  background: rgba(10, 9, 7, 0.72);
  backdrop-filter: blur(3px);
}

.modal-content {
  background: var(--bg-alt);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 24px;
  margin: 0;
}

.modal-content h2 {
  font-family: var(--font-display);
  font-weight: 700;
  letter-spacing: -0.01em;
  font-size: 22px;
  margin: 0 0 12px;
}

.modal-content p {
  font-size: 14.5px;
  line-height: 1.55;
  color: var(--text-dim);
  margin: 0 0 12px;
}

.modal-sub {
  font-size: 13px;
  color: var(--text-faint);
}

.example-box {
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 12px 14px;
  margin: 12px 0;
}
.example-label {
  font-size: 12px;
  color: var(--text-faint);
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.example-steps {
  font-family: var(--font-mono);
  font-size: 15px;
  color: var(--accent);
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.modal-actions {
  display: flex;
  gap: 10px;
  margin-top: 18px;
}
.modal-actions-end { justify-content: flex-end; }

.handle-input {
  width: 100%;
  font-family: var(--font-mono);
  font-size: 18px;
  letter-spacing: 0.01em;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--text);
}
.handle-input:focus { outline: 2px solid var(--accent); outline-offset: 1px; }

.handle-error {
  color: var(--bad);
  font-size: 13px;
  margin-top: 8px;
}

.stats-grid {
  display: flex;
  gap: 10px;
  margin-bottom: 18px;
}
.stat {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius-sm);
  padding: 14px 6px;
  text-align: center;
}
.stat-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 24px;
  font-weight: 700;
  color: var(--accent);
}
.stat-label {
  display: block;
  font-size: 11px;
  color: var(--text-faint);
  margin-top: 4px;
}

.star-histogram {
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.hist-row {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 12.5px;
  color: var(--text-dim);
}
.hist-row .hist-label { width: 44px; flex-shrink: 0; color: var(--accent); }
.hist-bar-track {
  flex: 1;
  height: 10px;
  background: var(--surface);
  border-radius: 6px;
  overflow: hidden;
}
.hist-bar-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 6px;
}
.hist-row .hist-count { width: 22px; text-align: right; font-family: var(--font-mono); color: var(--text-faint); }

/* ---------- toast ---------- */

.toast {
  position: fixed;
  bottom: 22px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--surface-raised);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 10px 18px;
  border-radius: 999px;
  font-size: 13.5px;
  z-index: 50;
  box-shadow: 0 10px 30px -10px rgba(0,0,0,0.6);
  animation: toast-in 0.25s ease;
}

@keyframes toast-in {
  from { opacity: 0; transform: translate(-50%, 8px); }
  to { opacity: 1; transform: translate(-50%, 0); }
}

/* ---------- footer ---------- */

.site-footer {
  width: 100%;
  max-width: 480px;
  margin-top: 48px;
  padding: 20px 18px 28px;
  border-top: 1px solid var(--border-soft);
  text-align: center;
  position: relative;
  z-index: 1;
}

.site-footer p {
  margin: 0 0 6px;
  font-size: 12.5px;
  color: var(--text-faint);
}
.site-footer p:last-child { margin-bottom: 0; }


.site-footer a {
  color: var(--text-dim);
  text-decoration: none;
  border-bottom: 1px dashed var(--text-faint);
}
.site-footer a:hover { color: var(--accent); border-color: var(--accent); }

.footer-support {
  color: var(--accent) !important;
  font-weight: 600;
  border-color: var(--accent) !important;
}
.footer-support:hover { color: var(--accent-strong) !important; border-color: var(--accent-strong) !important; }

/* ---------- keyboard focus ---------- */

button:focus-visible, .tile:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

@media (min-width: 520px) {
  :root { --tile-size: 86px; }
}