/* Night (default) theme — matches harshkakashaniya.github.io/Games/'s dark palette */
:root {
  --bg: #0d1117;
  --text: #e6edf3;
  --text-muted: #9aa7b3;
  --panel-bg: #161b22;
  --panel-border: #30363d;
  --accent: #58a6ff;
  --accent-text: #0d1117;
  /* Board gets its own genuinely light/dark palette — like lichess/chess.com,
     the board is a distinct visual zone and doesn't need to match the page
     chrome's dark tone. See docs/game/ux-guidelines.md's "Piece/board
     legibility" section for why (measured contrast bug, fixed 2026-08-29). */
  --board-light: #b7c4d6;
  --board-dark: #4c6485;
  --square-selected: #2f9e63;
  --square-legal-dot: rgba(230, 162, 20, 0.85);
  --square-capture-ring: #e5534b;
  --check-ring: #e5534b;
  --piece-white-fill: #ffffff;
  --piece-white-stroke: #000000;
  --piece-black-fill: #000000;
  --piece-black-stroke: #ffffff;
}

html[data-theme="light"] {
  --bg: #f5f7fa;
  --text: #1b1f24;
  --text-muted: #57606a;
  --panel-bg: #ffffff;
  --panel-border: #d7dde4;
  --accent: #2563eb;
  --accent-text: #ffffff;
  /* Classic warm wood-style board — proven-legible pairing, and the light
     theme has room to use it since it doesn't need to match a dark-site
     baseline the way night mode does. */
  --board-light: #f0e6d2;
  --board-dark: #b58863;
  --square-selected: #2f9e63;
  --square-legal-dot: rgba(191, 110, 20, 0.85);
  --square-capture-ring: #d64545;
  --check-ring: #d64545;
  /* Piece colors are theme-independent — pure black/white, defined once in :root. */
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.topbar {
  width: 100%;
  max-width: 560px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem;
}

.topbar h1 {
  font-size: 1.25rem;
  margin: 0;
}

.icon-btn {
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  color: var(--text);
  border-radius: 50%;
  width: 2.5rem;
  height: 2.5rem;
  font-size: 1.1rem;
  cursor: pointer;
}
.icon-btn:hover { border-color: var(--accent); }

main {
  width: 100%;
  max-width: 560px;
  padding: 0 1rem 2rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.panel {
  width: 100%;
  background: var(--panel-bg);
  border: 1px solid var(--panel-border);
  border-radius: 12px;
  padding: 1.5rem;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.75rem;
}

.panel.hidden { display: none; }

.panel h2 { margin: 0 0 0.25rem; }

.option-group {
  display: flex;
  gap: 0.5rem;
  width: 100%;
}

.option-btn {
  flex: 1;
  padding: 0.6rem 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--panel-border);
  background: transparent;
  color: var(--text);
  font-size: 0.95rem;
  cursor: pointer;
}

.option-btn.is-selected {
  background: var(--accent);
  color: var(--accent-text);
  border-color: var(--accent);
}

.option-hint {
  color: var(--text-muted);
  font-size: 0.85rem;
  margin: 0 0 0.5rem;
  text-align: center;
}

.primary-btn, .secondary-btn {
  padding: 0.7rem 1.5rem;
  border-radius: 8px;
  border: none;
  font-size: 1rem;
  cursor: pointer;
}

.primary-btn {
  background: var(--accent);
  color: var(--accent-text);
  font-weight: 600;
}

.secondary-btn {
  background: transparent;
  border: 1px solid var(--panel-border);
  color: var(--text);
  margin-top: 0.75rem;
}

.status-line {
  font-size: 1.05rem;
  font-weight: 600;
  min-height: 1.5em;
  text-align: center;
}
.status-line.is-check { color: var(--check-ring); }
.status-line.is-over { color: var(--accent); }

.board {
  width: min(90vw, 480px);
  aspect-ratio: 1 / 1;
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  border-radius: 6px;
  overflow: hidden;
  border: 1px solid var(--panel-border);
}

.square {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  padding: 0;
  cursor: pointer;
}

.square.light { background: var(--board-light); }
.square.dark { background: var(--board-dark); }

.square.is-selected { box-shadow: inset 0 0 0 3px var(--square-selected); }
.square.is-check { box-shadow: inset 0 0 0 3px var(--check-ring); }

.square .legal-dot {
  position: absolute;
  width: 22%;
  height: 22%;
  border-radius: 50%;
  background: var(--square-legal-dot);
  pointer-events: none;
}

.square .capture-ring {
  position: absolute;
  inset: 8%;
  border-radius: 50%;
  border: 3px solid var(--square-capture-ring);
  pointer-events: none;
}

/* Pieces are hand-drawn SVG silhouettes (game/js/piece-svgs.js), not Unicode
   glyphs — Unicode chess symbols render inconsistently across fonts/
   platforms and were reported as looking crude. Pure black/white fill
   (user preference — an earlier translucent backdrop-circle version
   measured well for contrast but was rejected on sight as "circles around
   the pieces"). Pure fill color only solves contrast on the *opposite*-
   toned square (white fill vs. dark square, black fill vs. light square) —
   a same-toned square (white piece on a light square, black piece on a
   dark square) is mathematically incapable of good fill-vs-background
   contrast no matter what shade of "light" or "dark" the square is,
   because that's what matching tones means. The outline stroke is what
   carries the same-toned cases, so it isn't optional polish — it's
   load-bearing. See docs/game/ux-guidelines.md's "Piece/board legibility"
   section for the measured numbers (this still holds with SVG shapes:
   `stroke` on an SVG shape is the direct equivalent of the old
   `-webkit-text-stroke`, and is standard/well-supported for vector shapes
   in every engine — no text-shadow fallback needed the way it was for
   Unicode glyphs). */
.piece-white, .piece-black {
  width: 82%;
  height: 82%;
  overflow: visible;
  pointer-events: none;
  stroke-width: 3;
  stroke-linejoin: round;
  stroke-linecap: round;
}
.piece-white { fill: var(--piece-white-fill); stroke: var(--piece-white-stroke); }
.piece-black { fill: var(--piece-black-fill); stroke: var(--piece-black-stroke); }

.promotion-picker {
  display: flex;
  gap: 0.5rem;
  background: var(--panel-bg);
  border: 1px solid var(--accent);
  border-radius: 8px;
  padding: 0.75rem;
}
.promotion-picker.hidden { display: none; }
.promotion-picker button {
  display: flex;
  align-items: center;
  justify-content: center;
  background: transparent;
  border: 1px solid var(--panel-border);
  border-radius: 6px;
  cursor: pointer;
  color: var(--text);
  width: 3rem;
  height: 3rem;
}
.promotion-picker button:hover { border-color: var(--accent); }

.foot-note {
  color: var(--text-muted);
  font-size: 0.8rem;
  padding: 1rem;
  text-align: center;
}