:root {
  --bg: #f4f1ea;
  --panel: #fffdf8;
  --ink: #23201c;
  --muted: #6f685e;
  --line: #ded7c9;
  --accent: #9a5b34;
  --accent-soft: #f0e2d6;
  --sq-light: #efe7d7;
  --sq-dark: #e2d6c0;
  --goal-w: #cfe0d2;
  --goal-b: #e4d3d3;
  --sel: #d8b45f;
  --target: #6f9c6b;
  --danger: #a8402f;
  --pc-fill: #fbf7ef;
  --pc-line: #2a2521;
  --radius: 10px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17151300;
    --bg: #171513;
    --panel: #201d1a;
    --ink: #ece5da;
    --muted: #9a9086;
    --line: #34302b;
    --accent: #d08a56;
    --accent-soft: #33261d;
    --sq-light: #4a423a;
    --sq-dark: #3d362f;
    --goal-w: #3a4a3d;
    --goal-b: #4d3a3a;
    --sel: #b8913f;
    --target: #79ad74;
    --danger: #d4674f;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font: 15px/1.5 ui-sans-serif, -apple-system, "Segoe UI", Roboto, sans-serif;
}

header {
  display: flex;
  align-items: baseline;
  gap: 24px;
  padding: 14px 24px;
  border-bottom: 1px solid var(--line);
  background: var(--panel);
}
header .brand { font-weight: 650; letter-spacing: -0.01em; }
header nav { display: flex; gap: 6px; }
header nav a {
  color: var(--muted);
  text-decoration: none;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 14px;
}
header nav a:hover { color: var(--ink); }
header nav a.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }

main {
  max-width: 1180px;
  margin: 0 auto;
  padding: 24px;
  display: grid;
  grid-template-columns: minmax(320px, 1fr) 360px;
  gap: 28px;
  align-items: start;
}
@media (max-width: 900px) {
  main { grid-template-columns: 1fr; }
}

/* ------------------------------------------------------------------ board */
.board-wrap {
  display: grid;
  grid-template-columns: 22px 1fr;
  grid-template-rows: 1fr 22px;
  gap: 4px;
  max-width: 620px;
}
.ranks, .files { display: grid; color: var(--muted); font-size: 11px; }
.ranks { grid-template-rows: repeat(9, 1fr); }
.files { grid-column: 2; grid-template-columns: repeat(9, 1fr); }
.ranks span { display: grid; place-items: center; }
.files span { display: grid; place-items: center; }

.board {
  grid-column: 2;
  display: grid;
  grid-template-columns: repeat(9, 1fr);
  grid-template-rows: repeat(9, 1fr);
  aspect-ratio: 1 / 1;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--sq-dark);
}

.sq {
  position: relative;
  display: grid;
  place-items: center;
  cursor: default;
  transition: background-color .12s;
}
.sq.light { background: var(--sq-light); }
.sq.dark { background: var(--sq-dark); }
.sq.goalw::before, .sq.goalb::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.sq.goalw::before { background: color-mix(in srgb, var(--goal-w) 62%, transparent); }
.sq.goalb::before { background: color-mix(in srgb, var(--goal-b) 62%, transparent); }
.board.interactive .sq.movable { cursor: pointer; }
.board.editing .sq { cursor: crosshair; }

.sq.sel { box-shadow: inset 0 0 0 4px var(--sel); }
.sq.lastfrom, .sq.lastto { background-image: linear-gradient(color-mix(in srgb, var(--sel) 45%, transparent), color-mix(in srgb, var(--sel) 45%, transparent)); }
.sq.hintfrom, .sq.hintto { box-shadow: inset 0 0 0 3px var(--accent); }

/* Move affordances: a dot for a quiet move, a ring for a capture. */
.sq.target::after {
  content: "";
  z-index: 2;
  position: absolute;
  width: 26%;
  height: 26%;
  border-radius: 50%;
  background: color-mix(in srgb, var(--target) 75%, transparent);
  pointer-events: none;
}
.sq.captarget::after {
  content: "";
  z-index: 2;
  position: absolute;
  inset: 8%;
  border-radius: 50%;
  border: 4px solid color-mix(in srgb, var(--danger) 80%, transparent);
  background: none;
  width: auto; height: auto;
  pointer-events: none;
}
.sq.target, .sq.captarget { cursor: pointer; }

.pc {
  width: 78%;
  height: 78%;
  pointer-events: none;
  display: block;
  position: relative;  /* keep pieces above the goal-file tint */
  z-index: 1;
}
/* Light core vs dark core is what separates the sides at a glance, so the two
   fills stay far apart in value and the rims only add definition. */
.pc-w { --pc-fill: #f8f4ec; --pc-line: #1b1714; }
.pc-b { --pc-fill: #15120f; --pc-line: #7d7266; }
.pc .ink { fill: var(--pc-fill); stroke: var(--pc-line); stroke-width: 6; stroke-linejoin: round; }
.pc .fold { fill: none; stroke: var(--pc-line); stroke-width: 5; stroke-linejoin: round; }
.pc .cut { fill: none; stroke: var(--pc-line); stroke-width: 20; stroke-linecap: round; }
.pc .cut-inner { stroke: var(--pc-fill); stroke-width: 13; }

/* ------------------------------------------------------------------ panel */
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 18px;
  margin-bottom: 16px;
}
.panel h2 {
  margin: 0 0 12px;
  font-size: 12px;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--muted);
  font-weight: 650;
}

.status { font-size: 17px; font-weight: 600; display: flex; align-items: center; gap: 9px; }
.status .dot { width: 13px; height: 13px; border-radius: 50%; border: 1px solid var(--pc-line); flex: none; }
.status .dot.w { background: #fbf7ef; }
.status .dot.b { background: #2b2622; }
.status.over { color: var(--accent); }
.substatus { color: var(--muted); font-size: 13px; margin-top: 4px; min-height: 19px; }

.row { display: flex; gap: 8px; flex-wrap: wrap; align-items: center; }
.row + .row { margin-top: 10px; }
.grow { flex: 1; }

button, select, input[type=text] {
  font: inherit;
  color: var(--ink);
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 6px 12px;
}
button { cursor: pointer; }
button:hover:not(:disabled) { border-color: var(--accent); color: var(--accent); }
button:disabled { opacity: .45; cursor: not-allowed; }
button.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
button.primary:hover:not(:disabled) { filter: brightness(1.08); color: #fff; }
label.field { display: flex; align-items: center; gap: 7px; font-size: 13px; color: var(--muted); }
label.field select { padding: 4px 8px; }

/* ------------------------------------------------------------ engine panel */
.eval {
  display: flex;
  align-items: baseline;
  gap: 10px;
  flex-wrap: wrap;
  font-variant-numeric: tabular-nums;
}
.eval .score { font-size: 26px; font-weight: 650; letter-spacing: -0.02em; }
.eval .score.long { font-size: 19px; }
.eval .meta { color: var(--muted); font-size: 12px; }

.lines { margin-top: 10px; display: flex; flex-direction: column; gap: 6px; }
.line {
  display: flex;
  gap: 10px;
  align-items: baseline;
  font-size: 13px;
  padding: 6px 8px;
  border-radius: 6px;
  background: var(--bg);
}
.line .ls { font-weight: 650; font-variant-numeric: tabular-nums; min-width: 52px; flex: none; }
.line .lp { display: flex; flex-wrap: wrap; gap: 2px 6px; }
.line .lp b { font-weight: 400; cursor: pointer; border-radius: 4px; padding: 0 3px; }
.line .lp b:hover { background: var(--accent-soft); color: var(--accent); }

.moves {
  max-height: 210px;
  overflow-y: auto;
  display: grid;
  grid-template-columns: 34px 1fr 1fr;
  gap: 2px 6px;
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}
.moves .n { color: var(--muted); text-align: right; }
.moves .m { cursor: pointer; padding: 1px 6px; border-radius: 4px; justify-self: start; }
.moves .m:hover { background: var(--accent-soft); }
.moves .m.cur { background: var(--accent); color: #fff; }

/* ----------------------------------------------------------------- editor */
.palette { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; }
.palette button {
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  padding: 4px;
  background: var(--sq-light);
}
.palette button.on { border-color: var(--accent); box-shadow: inset 0 0 0 2px var(--accent); }
.palette .pc { width: 82%; height: 82%; }
.palette .erase { font-size: 11px; color: var(--muted); }

.trace {
  display: flex;
  flex-wrap: wrap;
  gap: 3px 10px;
  margin-top: 9px;
  font-size: 11.5px;
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.warn { color: var(--danger); font-size: 12.5px; margin-top: 8px; }
.hint { color: var(--muted); font-size: 12.5px; margin-top: 8px; }
.posbox { width: 100%; font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: 12px; }
.legend { display: flex; gap: 14px; font-size: 12px; color: var(--muted); flex-wrap: wrap; }
.legend span { display: flex; align-items: center; gap: 5px; }
.legend .pc { width: 20px; height: 20px; }