/* Board page. Colors come from the tokens in /styles.css, so the board
   follows the site's palette in both light and dark mode. */

:root {
  /* Board colors: greens from the site palette, kept the same in dark mode
     so both white and black pieces stay easy to see on every square. */
  --board-light: #e6ede4;
  --board-dark: #7fa08a;
  --hl-last: rgba(214, 219, 92, 0.55);
  --hl-selected: rgba(24, 69, 59, 0.4);
  --hl-target: rgba(24, 69, 59, 0.38);
  --hl-check: rgba(214, 64, 52, 0.85);
}

.intro { margin: 0 0 32px; }

.game {
  display: grid;
  grid-template-columns: minmax(0, 560px) minmax(0, 300px);
  gap: clamp(24px, 4vw, 48px);
  align-items: start;
}

/* ---------- Board ---------- */

.board-wrap { position: relative; }

/* Named "chessboard" because the homepage already uses .board for its demo. */
.chessboard {
  touch-action: none;            /* dragging a piece shouldn't scroll the page */
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  aspect-ratio: 1;
  width: 100%;
  border-radius: var(--radius-sm);
  overflow: hidden;
  box-shadow: 0 0 0 2px var(--ink);
  user-select: none;
  container-type: inline-size;   /* lets pieces size themselves from the board width */
}

.sq {
  position: relative;
  min-width: 0;
  min-height: 0;
  appearance: none;
  border: 0;
  padding: 0;
  margin: 0;
  display: grid;
  place-items: center;
  cursor: default;
  font: inherit;
}
.sq.light { background: var(--board-light); }
.sq.dark  { background: var(--board-dark); }
.sq.movable { cursor: grab; }
.sq.target, .sq.target-capture { cursor: pointer; }
body.dragging, body.dragging .sq { cursor: grabbing; }

/* The piece being dragged: its home square shows a faded copy. */
.sq.drag-from img, .sq.drag-from .glyph { opacity: 0.3; }
.drag-ghost {
  position: fixed;
  z-index: 1000;
  pointer-events: none;
  transform: translate(-50%, -50%);
  display: grid;
  place-items: center;
}
.drag-ghost img { width: 100%; height: 100%; }
.drag-ghost .glyph { line-height: 1; }

/* Highlights are drawn as overlays so they combine with either square color. */
.sq::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
}
.sq.last::before     { background: var(--hl-last); }
.sq.selected::before { background: var(--hl-selected); }
.sq.check::before    { background: radial-gradient(circle, var(--hl-check) 0%, transparent 72%); }

/* Legal-move markers: a dot on empty squares, a ring around capturable pieces. */
.sq.target::after,
.sq.target-capture::after {
  content: "";
  position: absolute;
  pointer-events: none;
}
.sq.target::after {
  width: 30%;
  height: 30%;
  border-radius: 50%;
  background: var(--hl-target);
}
.sq.target-capture::after {
  inset: 4%;
  border-radius: 50%;
  border: 0.45em solid var(--hl-target);
}

/* Pieces are positioned over the square, so they can never stretch a row. */
.sq img,
.sq .glyph {
  position: absolute;
  inset: 6%;
  width: 88%;
  height: 88%;
  pointer-events: none;
}
.sq .glyph {
  display: grid;
  place-items: center;
  font-size: 10cqw;     /* 10% of the board's width */
  line-height: 1;
}
.glyph-w { color: #fbfbf8; text-shadow: 0 0 2px #111, 0 0 1px #111; }
.glyph-b { color: #161616; text-shadow: 0 0 2px rgba(255, 255, 255, 0.35); }

.coord {
  position: absolute;
  font-size: clamp(0.55rem, 1.4vw, 0.75rem);
  font-weight: 700;
  line-height: 1;
  pointer-events: none;
}
.sq.light .coord { color: var(--board-dark); }
.sq.dark .coord  { color: var(--board-light); }
.coord-rank { top: 4px; left: 4px; }
.coord-file { bottom: 3px; right: 4px; }

.sq:focus-visible { outline: 3px solid var(--green-lit); outline-offset: -3px; z-index: 1; }

/* ---------- Promotion picker ---------- */

.promo {
  position: absolute;
  inset: 0;
  display: grid;
  place-content: center;
  justify-items: center;
  gap: 12px;
  background: color-mix(in srgb, var(--paper) 85%, transparent);
  border-radius: var(--radius-sm);
}
.promo[hidden] { display: none; }
.promo p { margin: 0; font-weight: 700; }
.promo-choices { display: flex; gap: 8px; }
.promo-choice {
  width: clamp(56px, 12vw, 80px);
  aspect-ratio: 1;
  display: grid;
  place-items: center;
  border: 2px solid var(--rule);
  border-radius: var(--radius-sm);
  background: var(--board-light);
  cursor: pointer;
  padding: 0;
}
.promo-choice:hover { border-color: var(--green); }
.promo-choice img { width: 85%; height: 85%; }
.promo-choice .glyph { font-size: clamp(2.2rem, 8vw, 3.4rem); line-height: 1; }

/* ---------- Side panel ---------- */

.panel { display: grid; gap: 24px; }

.status {
  margin: 0;
  font-size: 1.25rem;
  font-weight: 700;
  min-height: 1.6em;
}
.status-error { color: #b3362c; font-size: 1rem; }

.controls { display: grid; gap: 10px; justify-items: start; }
.small-controls { display: flex; flex-wrap: wrap; gap: 4px 20px; }
.controls .button { width: 100%; text-align: center; border: 0; cursor: pointer; font: inherit; font-weight: 700; }
.button-secondary {
  background: transparent;
  color: var(--green);
  box-shadow: inset 0 0 0 2px var(--green);
}
.button-secondary:hover { background: var(--paper-2); color: var(--green); }
.button:disabled { opacity: 0.5; cursor: not-allowed; }

.text-button {
  appearance: none;
  background: none;
  border: 0;
  padding: 4px 0;
  color: var(--green);
  font: inherit;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}
.text-button:disabled { color: var(--ink-soft); opacity: 0.6; cursor: not-allowed; text-decoration: none; }

.think { display: grid; gap: 6px; font-weight: 600; font-size: 0.95rem; }
.think select {
  font: inherit;
  font-weight: 400;
  padding: 8px 10px;
  border: 1px solid var(--rule);
  border-radius: var(--radius-sm);
  background: var(--paper);
  color: var(--ink);
  max-width: 220px;
}

.moves h2 { font-size: 1.05rem; font-weight: 700; margin: 0 0 8px; }
.moves {
  max-height: 260px;
  overflow-y: auto;
  border-top: 1px solid var(--rule);
  padding-top: 12px;
}
.moves ol {
  margin: 0;
  padding-left: 2.2em;
  font-variant-numeric: tabular-nums;
  white-space: pre;
}
.moves li { padding: 1px 0; }

.source-link { margin-top: 40px; }

@media (max-width: 820px) {
  .game { grid-template-columns: 1fr; }
}