/* Bảng màu theo spec: bàn cố định, vỏ ngoài đổi theo data-theme. */
:root {
  --sq-light: #eeeed2;
  --sq-dark: #769656;
  --label-light: #769656;
  --label-dark: #eeeed2;
  --last-move: rgba(255, 213, 74, .35);
  --selected: #ffd54a;
  --dot-light: rgba(30, 30, 30, .28);
  --dot-dark: rgba(255, 255, 255, .55);
  --capture-ring: rgba(255, 80, 80, .95);
  --check: rgba(220, 60, 60, .55);
  --page: #15171c;
  --panel: #1e2229;
  --border: #2c313b;
  --fg: #e8e8e8;
  --muted: rgba(232, 232, 232, .6);
  --btn: #2a2f38;
  --btn-border: #3a4150;
  --btn-fg: #ddd;
  --turn: #2b3542;
}
html[data-theme="light"] {
  --page: #f2f2ef;
  --panel: #ffffff;
  --border: #dedcd5;
  --fg: #22242a;
  --muted: rgba(34, 36, 42, .6);
  --btn: #eceae4;
  --btn-border: #d6d3ca;
  --btn-fg: #333;
  --turn: #e8eefb;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 18px;
  background: var(--page);
  color: var(--fg);
  font: 14px/1.5 system-ui, "Segoe UI", sans-serif;
}

.app { display: flex; gap: 16px; align-items: flex-start; max-width: 960px; margin: 0 auto; }
.board-area { flex: 1 1 auto; min-width: 0; }

.board {
  position: relative;
  width: min(640px, 100%);
  aspect-ratio: 1;
  margin: 0 auto;
  border-radius: 4px;
  overflow: hidden;
}

/* Hai lớp: ô vuông bên dưới, quân bên trên. Nhờ tách vậy quân trượt
   bằng CSS transition chỉ cần đổi transform. */
.squares, .pieces { position: absolute; inset: 0; display: grid; grid-template-columns: repeat(8, 1fr); }
.squares { z-index: 1; }
.pieces  { z-index: 2; pointer-events: none; }

.sq { position: relative; }
.sq.light { background: var(--sq-light); }
.sq.dark  { background: var(--sq-dark); }
.sq.last::before { content: ""; position: absolute; inset: 0; background: var(--last-move); }
.sq.sel   { box-shadow: inset 0 0 0 4px var(--selected); }
.sq.check { box-shadow: inset 0 0 0 4px var(--check); }

.sq .dot  { position: absolute; inset: 37%; border-radius: 50%; }
.sq.light .dot { background: var(--dot-light); }
.sq.dark  .dot { background: var(--dot-dark); }
.sq .ring { position: absolute; inset: 1%; border-radius: 50%; border: 4px solid var(--capture-ring); }

.sq .coord { position: absolute; font-size: 11px; font-weight: 600; line-height: 1; opacity: .75; }
.sq .coord.file { right: 3px; bottom: 2px; }
.sq .coord.rank { left: 3px; top: 2px; }
.sq.light .coord { color: var(--label-light); }
.sq.dark  .coord { color: var(--label-dark); }

/* Quân: kích thước cố định, CHỈ transform đổi nên transition chạy mượt. */
.piece {
  position: absolute;
  width: 12.5%;
  height: 12.5%;
  transition: transform .15s ease;
  will-change: transform;
}
.piece img { width: 100%; height: 100%; display: block; }

.picker { position: absolute; z-index: 3; display: flex; flex-wrap: wrap; width: 12.5%; gap: 2px; }
.picker button { flex: 1 1 45%; aspect-ratio: 1; border: 1px solid var(--border); background: var(--panel); border-radius: 3px; padding: 1px; cursor: pointer; }
.picker img { width: 100%; height: 100%; }

.panel { width: 260px; flex: none; background: var(--panel); border: 1px solid var(--border); border-radius: 8px; padding: 12px; }
.panel-head { display: flex; align-items: center; justify-content: space-between; margin-bottom: 10px; }
.brand { font-weight: 700; letter-spacing: .02em; }
.icon-btn { background: var(--btn); color: var(--btn-fg); border: 1px solid var(--btn-border); border-radius: 5px; width: 30px; height: 26px; cursor: pointer; }

.player { display: flex; align-items: center; gap: 8px; padding: 6px 8px; border-radius: 6px; }
.player.turn { background: var(--turn); }
.player .dot { width: 11px; height: 11px; border-radius: 50%; border: 1px solid #888; flex: none; }
.player .dot.white { background: #f2f2f2; }
.player .dot.black { background: #3a3f4a; }
.player div { display: flex; flex-direction: column; }
.player small { color: var(--muted); font-size: 11px; }
.captured { margin-left: auto; display: flex; gap: 1px; align-items: center; }
.captured img { width: 15px; height: 15px; }

.message { min-height: 20px; margin: 10px 0 6px; color: var(--muted); font-size: 13px; }
.message.error { color: #ff8a80; }

.moves { list-style: none; margin: 0; padding: 0; display: grid; grid-template-columns: auto 1fr 1fr; gap: 1px 8px; font-size: 13px; max-height: 190px; overflow: auto; font-variant-numeric: tabular-nums; }
.moves li { color: var(--muted); }
.moves li.w, .moves li.b { color: var(--fg); }
.moves li.now { background: var(--turn); border-radius: 3px; }

.actions { display: grid; grid-template-columns: 1fr 1fr; gap: 6px; margin-top: 12px; }
.actions button { padding: 7px 8px; font-size: 13px; background: var(--btn); color: var(--btn-fg); border: 1px solid var(--btn-border); border-radius: 5px; cursor: pointer; }
.actions button.primary { background: #4a7dd6; border-color: #4a7dd6; color: #fff; }
.actions button:disabled { opacity: .45; cursor: not-allowed; }

@media (max-width: 720px) {
  .app { flex-direction: column; }
  .panel { width: 100%; }
  .moves { max-height: 120px; }
}

/* ---- #3B: hộp chọn phe + Elo, và trạng thái "AI đang nghĩ" ---- */
.setup {
  margin-top: 12px; padding: 10px;
  border: 1px solid var(--border); border-radius: 6px;
  display: grid; gap: 8px;
}
.setup[hidden] { display: none; }
.setup-row { display: grid; gap: 4px; }
.setup-label { font-size: 12px; color: var(--muted); }
.setup-label b { color: var(--fg); }
.seg { display: flex; gap: 4px; }
.seg button {
  flex: 1; padding: 5px; font-size: 12px;
  background: var(--btn); color: var(--btn-fg);
  border: 1px solid var(--btn-border); border-radius: 4px; cursor: pointer;
}
.seg button.on { background: #4a7dd6; border-color: #4a7dd6; color: #fff; }
#elo { width: 100%; accent-color: #4a7dd6; }
.player small + small { opacity: .85; }
.thinking::after { content: " …"; animation: nhapnhay 1s steps(3) infinite; display: inline-block; }
@keyframes nhapnhay { 0% { opacity: .2; } 50% { opacity: 1; } 100% { opacity: .2; } }
.squares.locked { cursor: default; }
.squares.locked .piece { filter: saturate(.85); }
@media (prefers-reduced-motion: reduce) {
  .thinking::after { animation: none; }
  .piece { transition: none; }
}

/* ---- #3C: ba man, danh sach phong, phong cho ---- */
.tabs { display: flex; gap: 4px; margin-bottom: 10px; }
.tabs button {
  flex: 1; padding: 5px; font-size: 12px; cursor: pointer;
  background: var(--btn); color: var(--btn-fg);
  border: 1px solid var(--btn-border); border-radius: 4px;
}
.tabs button.on { background: #4a7dd6; border-color: #4a7dd6; color: #fff; }
.view[hidden] { display: none; }
.home { display: grid; gap: 6px; }
.home button, .lobby button, .waiting button {
  padding: 7px 8px; font-size: 13px; cursor: pointer;
  background: var(--btn); color: var(--btn-fg);
  border: 1px solid var(--btn-border); border-radius: 5px;
}
.home button.primary, .waiting button.primary { background: #4a7dd6; border-color: #4a7dd6; color: #fff; }
.home button.primary:disabled, .waiting button:disabled { opacity: .45; cursor: not-allowed; }
.join-row, .invite-row { display: flex; gap: 4px; margin-top: 6px; }
.join-row input, .invite-row input {
  flex: 1; min-width: 0; padding: 5px 6px; font-size: 12px;
  background: var(--page); color: var(--fg);
  border: 1px solid var(--btn-border); border-radius: 4px;
}
.room-list { list-style: none; margin: 8px 0 0; padding: 0; display: grid; gap: 4px; max-height: 190px; overflow: auto; }
.room-list li {
  display: flex; align-items: center; gap: 6px; padding: 5px 7px;
  border: 1px solid var(--border); border-radius: 5px; font-size: 12px;
}
.room-list li.empty { color: var(--muted); display: block; }
.room-list .ma { font-family: ui-monospace, monospace; font-weight: 600; }
.room-list .trang { margin-left: auto; color: var(--muted); }
.room-list button { padding: 3px 8px; font-size: 12px; }
.room-list button:disabled { opacity: .4; cursor: not-allowed; }
.room-code { font-family: ui-monospace, monospace; font-size: 20px; text-align: center; margin: 0 0 8px; }
.seats { list-style: none; margin: 0 0 8px; padding: 0; display: grid; gap: 4px; font-size: 13px; }
.seats .dot { display: inline-block; width: 10px; height: 10px; border-radius: 50%; border: 1px solid #888; }
.seats .dot.white { background: #f2f2f2; }
.seats .dot.black { background: #3a3f4a; }
.note { font-size: 12px; color: var(--muted); margin: 6px 0; }
.room-status { margin: 4px 0 0; font-size: 12px; color: var(--muted); }
.room-status[hidden] { display: none; }
.room-status.warn { color: #ffb45a; }