*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg:       #0c0c18;
  --surface:  #13131f;
  --border:   rgba(255,255,255,0.08);
  --accent:   #7c3aed;
  --accent2:  #2563eb;
  --text:     rgba(255,255,255,0.88);
  --text-dim: rgba(255,255,255,0.35);
  --danger:   #f87171;
  --board-w:  248px;
}

html, body {
  min-height: 100%;
  background: var(--bg);
  color: var(--text);
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 14px;
}

/* ── Header ─────────────────────────────────────────── */
header {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 12px 24px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
}
.header-brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  margin-right: auto;
}
.logo {
  font-size: 1rem;
  font-weight: 900;
  letter-spacing: 0.22em;
  background: linear-gradient(135deg, #a78bfa, #60a5fa);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.logo-sub {
  font-size: 0.78rem;
  letter-spacing: 0.15em;
  color: var(--text-dim);
  text-transform: uppercase;
}
.header-controls {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}
.header-select {
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text);
  padding: 5px 10px;
  font-size: 0.82rem;
  appearance: none;
  cursor: pointer;
  outline: none;
  transition: border-color 0.15s;
}
.header-select:focus { border-color: var(--accent); }
#btn-new {
  padding: 6px 14px;
  background: linear-gradient(135deg, var(--accent), var(--accent2));
  border: none;
  border-radius: 7px;
  color: #fff;
  font-weight: 700;
  font-size: 0.82rem;
  letter-spacing: 0.06em;
  cursor: pointer;
  white-space: nowrap;
  transition: opacity 0.15s, transform 0.1s;
}
#btn-new:hover  { opacity: 0.88; }
#btn-new:active { transform: scale(0.97); }


/* ── Universes section ───────────────────────────────── */
.universes-section {
  padding: 20px 24px 40px;
}
.universes-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, 260px);
  gap: 16px;
  align-items: start;
}

/* ── Board wrap (main board) ─────────────────────────── */
.board-wrap {
  display: flex;
  flex-direction: column;
  gap: 4px;
  position: relative;
  width: 260px;      /* 248px board + 6px padding each side */
  padding: 6px;
  overflow: hidden;  /* board squares can't escape the fixed container */
}
#board { width: 248px !important; }

/* D3 overlay */
.d3-overlay { overflow: visible; }

/* chessboard.js square colours */
.white-1e1d7 { background-color: #e8e0f4 !important; }
.black-3c85d { background-color: #5b3fa0 !important; }
/* Fork boards: dark squares use the card's palette colour */
.fork-card .black-3c85d { background-color: var(--sq-dark, #5b3fa0) !important; }

/* Last-move highlight */
.highlight-from { box-shadow: inset 0 0 0 4px rgba(251,191,36,0.8) !important; }
.highlight-to   { box-shadow: inset 0 0 0 4px rgba(251,191,36,0.8) !important; }

/* ── Thinking indicator ──────────────────────────────── */
.thinking-dot {
  color: var(--accent);
  font-size: 0.5rem;
  opacity: 0;
}
.thinking-dot.active {
  opacity: 1;
  animation: blink 1s ease-in-out infinite;
}
@keyframes blink {
  0%, 100% { opacity: 0; }
  50%       { opacity: 1; }
}

/* ── Fork card — every universe shares this ──────────── */
.fork-card {
  background: var(--surface);
  border: 1px solid var(--fork-border, var(--accent));
  border-radius: 12px;
  overflow: hidden;
  width: 260px;
  box-shadow: 0 0 24px var(--fork-glow, rgba(124,58,237,0.15));
  opacity: 0;
  transform: translateY(12px) scale(0.97);
  transition: opacity 0.3s ease, transform 0.3s ease, box-shadow 0.2s;
}
.fork-card.fork-visible {
  opacity: 1;
  transform: none;
}
.fork-card.fork-exiting {
  opacity: 0;
  transform: translateY(8px) scale(0.96);
}
.fork-card:hover {
  box-shadow: 0 0 36px var(--fork-glow, rgba(124,58,237,0.25));
}

/* Main universe — skip entry animation, brighter glow */
.board-card {
  --fork-glow: rgba(124,58,237,0.28);
  opacity: 1;
  transform: none;
}

.fork-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
}
.fork-origin {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--fork-label, var(--accent));
  letter-spacing: 0.04em;
}
.fork-actions { display: flex; gap: 2px; }
.fork-btn {
  background: transparent;
  border: none;
  color: var(--text-dim);
  font-size: 0.9rem;
  cursor: pointer;
  padding: 2px 5px;
  border-radius: 4px;
  line-height: 1;
  transition: color 0.15s, background 0.15s;
}
.fork-btn:disabled          { opacity: 0.25; cursor: default; pointer-events: none; }
.fork-btn:hover             { color: var(--text); background: rgba(255,255,255,0.06); }
.fork-btn-fork:hover        { color: var(--fork-label, var(--accent)); }
.fork-btn-promote:hover     { color: #34d399; }
.fork-btn-close:hover       { color: var(--danger); }

.fork-board-wrap {
  width: 260px;
  padding: 6px;
  overflow: hidden;
}
.fork-board-el { width: 248px !important; }

.fork-universes {
  border-top: 1px solid var(--border);
  padding: 6px 6px 4px;
}
.fork-universe-header {
  font-size: 0.6rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--fork-label, var(--text-dim));
  opacity: 0.5;
  padding: 0 4px 4px;
}
.fork-universe-list { display: flex; flex-direction: column; gap: 3px; }

.fork-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 6px 10px;
  border-top: 1px solid var(--border);
}
.fork-status         { font-size: 0.72rem; color: var(--text-dim); transition: color 0.2s; }
.fork-status.active  { color: var(--text); }
.fork-status.check   { color: #fbbf24; }
.fork-status.over    { color: var(--danger); font-weight: 600; }
.fork-side {
  font-size: 0.68rem;
  color: var(--fork-label, var(--accent));
  opacity: 0.6;
}

/* ── Universe branch cards ───────────────────────────── */
.u-card {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 4px 8px;
  border-radius: 6px;
  background: color-mix(in srgb, var(--fork-border, #7c3aed) 8%, transparent);
  border: 1px solid color-mix(in srgb, var(--fork-border, #7c3aed) 20%, transparent);
  font-size: 0.72rem;
  min-height: 28px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.1s;
  user-select: none;
}
.u-card:first-child {
  background: color-mix(in srgb, var(--fork-border, #7c3aed) 15%, transparent);
  border-color: color-mix(in srgb, var(--fork-border, #7c3aed) 38%, transparent);
}
.u-card:hover {
  background: color-mix(in srgb, var(--fork-border, #7c3aed) 18%, transparent);
  border-color: color-mix(in srgb, var(--fork-border, #7c3aed) 50%, transparent);
  transform: translateY(-1px);
}
.u-card:active {
  transform: scale(0.98);
  background: color-mix(in srgb, var(--fork-border, #7c3aed) 25%, transparent);
}
.u-id {
  font-size: 0.65rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--fork-label, var(--accent));
  opacity: 0.7;
  min-width: 18px;
}
.u-moves {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 2px;
  flex: 1;
  overflow: hidden;
}
.u-move {
  font-family: 'Courier New', monospace;
  font-size: 0.7rem;
  color: var(--text);
  white-space: nowrap;
}
.u-sep { color: var(--text-dim); font-size: 0.7rem; line-height: 1; }
.u-score {
  font-size: 0.68rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  min-width: 30px;
  text-align: right;
  flex-shrink: 0;
}
.score-good { color: #34d399; }
.score-bad  { color: #f87171; }
.score-eq   { color: var(--text-dim); }
/* Selected square (click-to-move) */
.highlight-selected { box-shadow: inset 0 0 0 4px rgba(167,139,250,0.85) !important; }

/* ── Responsive ──────────────────────────────────────── */
@media (max-width: 640px) {
  header {
    flex-direction: column;
    align-items: stretch;
    gap: 10px;
    padding: 12px 16px;
  }
  .header-brand    { margin-right: 0; }
  .header-controls {
    gap: 8px;
    flex-wrap: nowrap;
  }
  .header-select {
    flex: 1;
    min-width: 0;
    font-size: 0.82rem;
    padding: 8px 10px;
    text-align: center;
  }
  #btn-new {
    flex-shrink: 0;
    padding: 8px 18px;
  }

  .universes-section { padding: 16px 12px 32px; }
  .universes-grid    { grid-template-columns: 1fr; }
  .fork-card         { width: 100%; }
  .board-wrap,
  .fork-board-wrap   { width: 100%; }
  #board,
  .fork-board-el     { width: 100% !important; }
}