:root {
  --bg: #14110e;
  --panel: #211c17;
  --panel-2: #2c241c;
  --ink: #f3ece1;
  --muted: #a99c88;
  --accent: #c9a24a;        /* warm gold */
  --accent-ink: #1a1408;
  --light-sq: #f0d9b5;
  --dark-sq: #b58863;
  --good: #5fb85f;
  --bad: #d9534f;
  --hint: #4f9bd9;
  --border: #3a3026;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

* { box-sizing: border-box; }
html, body { margin: 0; background: var(--bg); color: var(--ink); }
body { padding: 18px; }

header.top {
  display: flex; align-items: baseline; gap: 14px; flex-wrap: wrap;
  border-bottom: 1px solid var(--border); padding-bottom: 12px; margin-bottom: 16px;
}
header.top h1 { font-size: 20px; margin: 0; letter-spacing: .5px; }
header.top h1 .gold { color: var(--accent); }
header.top .tag { color: var(--muted); font-size: 13px; }
#side-indicator { margin-left: auto; font-size: 14px; color: var(--muted); }
#side-indicator strong { color: var(--ink); }

.layout { display: grid; grid-template-columns: minmax(320px, 560px) 1fr; gap: 22px; align-items: start; }
@media (max-width: 860px) { .layout { grid-template-columns: 1fr; } }

/* ---------------- board ---------------- */
.board-col { display: flex; flex-direction: column; gap: 12px; }
#board {
  width: 100%; max-width: 560px; aspect-ratio: 1 / 1;
  display: grid; grid-template-columns: repeat(8, 1fr); grid-template-rows: repeat(8, 1fr);
  border: 3px solid #6b4a2e; border-radius: 6px; overflow: hidden;
  box-shadow: 0 10px 30px rgba(0,0,0,.45);
  user-select: none;
}
#board.locked { cursor: default; }
.sq { position: relative; display: flex; align-items: center; justify-content: center; }
.sq.light { background: var(--light-sq); }
.sq.dark  { background: var(--dark-sq); }

.coord { position: absolute; font-size: 11px; font-weight: 700; opacity: .65; pointer-events: none; }
.coord.rank { top: 2px; left: 3px; }
.coord.file { bottom: 1px; right: 4px; }
.sq.light .coord { color: #8a6a45; }
.sq.dark  .coord { color: #f0d9b5; }

/* pieces: large vector sprite, with a contrast halo so they read on any square
 * (white pieces get a dark edge, black pieces get a light edge). */
.piece {
  width: 94%; height: 94%;
  cursor: grab; pointer-events: auto;
  -webkit-user-select: none; user-select: none;
  display: block;
  transition: transform .05s ease;
}
.piece:active { cursor: grabbing; }
.piece.white {
  filter: drop-shadow(0 0 1.1px #15110a) drop-shadow(0 1px 1.5px rgba(0,0,0,.45));
}
.piece.black {
  filter: drop-shadow(0 0 1.1px #f6f3ec) drop-shadow(0 0 1.6px rgba(255,255,255,.65))
          drop-shadow(0 1px 1.5px rgba(0,0,0,.35));
}
#board.locked .piece { cursor: default; }

/* highlights */
.sq.last-from, .sq.last-to { box-shadow: inset 0 0 0 100px rgba(201,162,74,.30); }
.sq.selected  { box-shadow: inset 0 0 0 100px rgba(95,184,95,.35); }
.sq.in-check  { box-shadow: inset 0 0 0 100px rgba(217,83,79,.45); }
.sq.target::after {
  content: ""; position: absolute; width: 30%; height: 30%; border-radius: 50%;
  background: rgba(20,20,20,.30);
}
.sq.target-capture::after {
  content: ""; position: absolute; inset: 8%; border-radius: 50%;
  border: 5px solid rgba(20,20,20,.30);
}
.sq.good { animation: flashGood .65s ease; }
.sq.bad  { animation: flashBad .65s ease; }
.sq.hint-from { box-shadow: inset 0 0 0 100px rgba(79,155,217,.30); }
.sq.hint-to   { box-shadow: inset 0 0 0 100px rgba(79,155,217,.45); }
@keyframes flashGood { 0%,100%{box-shadow:none;} 40%{box-shadow: inset 0 0 0 100px rgba(95,184,95,.55);} }
@keyframes flashBad  { 0%,100%{box-shadow:none;} 40%{box-shadow: inset 0 0 0 100px rgba(217,83,79,.6);} }

/* feedback + controls under the board */
.feedback { background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 12px 14px; min-height: 64px; }
#instruction { font-size: 14px; color: var(--muted); margin-bottom: 6px; }
.fb-title { font-size: 16px; font-weight: 700; }
.fb-title.good { color: var(--good); }
.fb-title.bad  { color: var(--bad); }
.fb-title.neutral { color: var(--accent); }
#fb-detail { font-size: 14px; color: var(--ink); margin-top: 4px; line-height: 1.45; }
.opp-line { font-size: 13px; margin-top: 8px; line-height: 1.4; }
.opp-line:empty { margin-top: 0; }
.opp-line .opp-move { color: var(--accent); font-weight: 600; }
.opp-line .opp-note { color: var(--muted); }

.controls { display: flex; gap: 8px; flex-wrap: wrap; }
button.btn {
  background: var(--panel-2); color: var(--ink); border: 1px solid var(--border);
  padding: 9px 14px; border-radius: 8px; font-size: 14px; cursor: pointer;
}
button.btn:hover { border-color: var(--accent); }
button.btn.primary { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 700; }
button.btn.danger:hover { border-color: var(--bad); color: var(--bad); }

/* ---------------- sidebar ---------------- */
.side { display: flex; flex-direction: column; gap: 16px; }
.card { background: var(--panel); border: 1px solid var(--border); border-radius: 10px; padding: 14px; }
.card h2 { font-size: 13px; text-transform: uppercase; letter-spacing: 1px; color: var(--muted); margin: 0 0 10px; }

#opening-list { display: flex; flex-wrap: wrap; gap: 8px; }
.op-btn {
  background: var(--panel-2); color: var(--ink); border: 1px solid var(--border);
  padding: 8px 12px; border-radius: 999px; font-size: 14px; cursor: pointer;
}
.op-btn.active { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 700; }
#opening-summary { font-size: 13px; color: var(--muted); line-height: 1.5; margin-top: 10px; }

#variation-list { display: flex; flex-wrap: wrap; gap: 8px; }
.chip {
  background: var(--panel-2); color: var(--ink); border: 1px solid var(--border);
  padding: 7px 12px; border-radius: 8px; font-size: 14px; cursor: pointer; text-align: left;
  display: flex; flex-direction: column; line-height: 1.2;
}
.chip small { color: var(--muted); font-size: 11px; margin-top: 2px; }
.chip.active { background: var(--accent); color: var(--accent-ink); border-color: var(--accent); font-weight: 700; }
.chip.active small { color: rgba(26,20,8,.7); }

#movelist { display: flex; flex-wrap: wrap; gap: 6px 12px; font-size: 14px; font-variant-numeric: tabular-nums; }
#movelist .mv b { color: var(--muted); font-weight: 600; margin-right: 2px; }
.muted { color: var(--muted); }

table.stats { width: 100%; border-collapse: collapse; font-size: 13px; }
table.stats th { text-align: left; color: var(--muted); font-weight: 600; padding: 4px 6px; border-bottom: 1px solid var(--border); }
table.stats td { padding: 6px; border-bottom: 1px solid rgba(58,48,38,.5); }
.badge { padding: 2px 8px; border-radius: 999px; font-size: 11px; font-weight: 700; }
.badge.new { background: #3a3026; color: var(--muted); }
.badge.learning { background: #5a4a1e; color: #f0d59a; }
.badge.practiced { background: #2f5a3a; color: #b9f0c6; }
.badge.mastered { background: var(--accent); color: var(--accent-ink); }

footer { margin-top: 22px; color: var(--muted); font-size: 12px; text-align: center; }
footer a { color: var(--accent); }