:root {
  --bg-top: #f8f1de;
  --bg-bottom: #ecd9bd;
  --panel: rgba(255, 251, 244, 0.9);
  --panel-border: #e1ceb1;
  --ink: #2b241d;
  --muted: #6e6254;
  --accent: #bc5d2d;
  --accent-dark: #95451e;
  --secondary: #66594d;
  --secondary-dark: #51463d;
  --success: #2f7b57;
  --success-dark: #235b40;
  --grid: #e6d7bf;
  --tile: #fffdf8;
  --highlight: #fff1dc;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Segoe UI", "Noto Sans TC", sans-serif;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(255, 247, 210, 0.95) 0%, transparent 34%),
    radial-gradient(circle at top right, rgba(255, 224, 193, 0.8) 0%, transparent 28%),
    linear-gradient(180deg, var(--bg-top) 0%, var(--bg-bottom) 100%);
  padding: 20px;
}

.app {
  width: min(1180px, 100%);
  margin: 0 auto;
  background: var(--panel);
  backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.45);
  border-radius: 28px;
  padding: 24px;
  box-shadow: 0 24px 60px rgba(73, 46, 16, 0.14);
  overflow-x: clip;
}

.header h1 {
  margin: 0;
  font-size: clamp(2rem, 3vw, 2.6rem);
  letter-spacing: 0.04em;
}

.header p {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 1rem;
}

.layout {
  display: grid;
  grid-template-columns: minmax(300px, 360px) minmax(0, 1fr);
  gap: 22px;
  margin-top: 22px;
  align-items: start;
}

.sidebar,
.game-area {
  min-width: 0;
}

.sidebar {
  display: grid;
  gap: 16px;
}

.panel {
  background: rgba(255, 255, 255, 0.74);
  border: 1px solid var(--panel-border);
  border-radius: 20px;
  padding: 18px;
  box-shadow: 0 14px 30px rgba(83, 57, 27, 0.08);
}

.panel-header {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}

.panel-header h2 {
  margin: 0;
  font-size: 1.1rem;
}

.panel-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  justify-content: flex-end;
}

.field-group + .field-group {
  margin-top: 16px;
}

.field-group label,
.status-label {
  display: inline-block;
  font-weight: 700;
  margin-bottom: 8px;
}

.field-hint {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
  min-height: 1.3em;
}

.inline-field {
  display: flex;
  gap: 10px;
}

input,
select,
button {
  font: inherit;
}

input,
select {
  width: 100%;
  border: 1px solid #d6c4a9;
  border-radius: 12px;
  padding: 10px 12px;
  background: #fffdf9;
  color: var(--ink);
}

button {
  border: 1px solid transparent;
  border-radius: 12px;
  padding: 10px 14px;
  color: #fff;
  background: var(--accent);
  cursor: pointer;
  transition:
    transform 0.12s ease,
    background-color 0.15s ease,
    box-shadow 0.15s ease;
  box-shadow: 0 8px 18px rgba(188, 93, 45, 0.22);
}

button:hover:not(:disabled) {
  transform: translateY(-1px);
  background: var(--accent-dark);
}

button:disabled {
  opacity: 0.55;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.secondary-btn {
  background: var(--secondary);
  box-shadow: 0 8px 18px rgba(102, 89, 77, 0.18);
}

.secondary-btn:hover:not(:disabled) {
  background: var(--secondary-dark);
}

.success-btn {
  background: var(--success);
  box-shadow: 0 8px 18px rgba(47, 123, 87, 0.22);
}

.success-btn:hover:not(:disabled) {
  background: var(--success-dark);
}

.ghost-btn {
  color: var(--secondary);
  background: rgba(255, 255, 255, 0.8);
  border-color: #d8c6ad;
  box-shadow: none;
}

.ghost-btn:hover:not(:disabled) {
  background: #fff;
}

.button-row {
  margin-top: 18px;
  display: grid;
  gap: 10px;
}

.status-panel {
  display: grid;
  gap: 12px;
}

.status-actions {
  display: flex;
  justify-content: flex-end;
}

.status-actions button {
  min-width: 160px;
}

.replay-controls {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
}

.replay-status {
  min-width: 68px;
  text-align: center;
  color: var(--muted);
  font-weight: 700;
}

.replay-arrow-btn {
  width: 46px;
  min-width: 46px;
  height: 46px;
  padding: 0;
  font-size: 1.25rem;
  line-height: 1;
}

.status-item {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 10px;
  border-bottom: 1px solid rgba(225, 206, 177, 0.75);
}

.status-item strong {
  font-size: 1.1rem;
}

.message,
.rank-update-status {
  margin: 0;
  min-height: 1.5em;
  font-weight: 700;
}

.message {
  color: var(--success-dark);
}

.rank-update-status {
  color: var(--muted);
  font-weight: 600;
}

.preview-frame {
  aspect-ratio: 1;
  width: min(100%, 300px);
  margin: 0 auto;
  border-radius: 18px;
  border: 1px solid #ead8bd;
  background:
    linear-gradient(45deg, rgba(232, 215, 190, 0.35) 25%, transparent 25%),
    linear-gradient(-45deg, rgba(232, 215, 190, 0.35) 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, rgba(232, 215, 190, 0.35) 75%),
    linear-gradient(-45deg, transparent 75%, rgba(232, 215, 190, 0.35) 75%);
  background-size: 28px 28px;
  background-position: 0 0, 0 14px, 14px -14px, -14px 0;
  display: grid;
  place-items: center;
  overflow: hidden;
}

.preview img {
  width: 100%;
  height: 100%;
  object-fit: contain;
  display: block;
  background: rgba(255, 255, 255, 0.8);
}

.game-area {
  display: grid;
  min-width: 0;
  gap: 16px;
}

.board-wrap {
  display: grid;
  place-items: center;
  min-height: 100%;
  width: 100%;
  min-width: 0;
  background:
    radial-gradient(circle at top, rgba(255, 249, 235, 0.8), rgba(255, 255, 255, 0.2)),
    rgba(250, 242, 231, 0.7);
  border: 1px solid var(--panel-border);
  border-radius: 24px;
  padding: 16px;
  overflow: hidden;
}

.board {
  width: min(100%, 720px);
  max-width: 100%;
  aspect-ratio: 1;
  display: grid;
  gap: 4px;
  padding: 8px;
  background: linear-gradient(180deg, #eadfcf 0%, var(--grid) 100%);
  border: 1px solid #dfceb4;
  border-radius: 12px;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.55);
}

.board[data-size="5"],
.board[data-size="6"] {
  gap: 3px;
  padding: 6px;
}

.tile {
  position: relative;
  border: 0;
  border-radius: 0;
  background-color: var(--tile);
  background-repeat: no-repeat;
  background-origin: border-box;
  box-shadow:
    0 1px 0 rgba(0, 0, 0, 0.04),
    0 4px 10px rgba(65, 44, 24, 0.12);
  cursor: pointer;
  transition: transform 0.08s ease, box-shadow 0.12s ease;
  overflow: hidden;
}

.tile:hover {
  transform: translateY(-1px);
  box-shadow:
    0 1px 0 rgba(0, 0, 0, 0.04),
    0 6px 14px rgba(65, 44, 24, 0.16);
}

.tile:focus-visible {
  outline: 3px solid #4f9dff;
  outline-offset: 2px;
}

.tile.empty {
  background: rgba(255, 255, 255, 0.25);
  border: 1px dashed rgba(111, 98, 83, 0.34);
  box-shadow: none;
  cursor: default;
}

.tile-index {
  position: absolute;
  top: 4px;
  left: 4px;
  min-width: 1.8em;
  padding: 1px 4px;
  background: rgba(43, 36, 29, 0.74);
  color: #fff;
  font-size: clamp(0.55rem, 1.8vw, 0.72rem);
  line-height: 1.2;
  text-align: center;
  pointer-events: none;
}

.tile.empty .tile-index {
  background: rgba(102, 89, 77, 0.68);
}

.leaderboard-panel {
  margin-top: 22px;
}

.leaderboard-list {
  list-style: none;
  padding: 0;
  margin: 14px 0 0;
  display: grid;
  gap: 10px;
}

.leaderboard-item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 10px 12px;
  align-items: center;
  padding: 12px 14px;
  border-radius: 14px;
  background: rgba(255, 248, 238, 0.9);
  border: 1px solid #ead8bf;
}

.leaderboard-item.current-player {
  background: var(--highlight);
}

.leaderboard-rank {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 999px;
  font-weight: 800;
  background: #fff;
  border: 1px solid #e6d4bc;
}

.leaderboard-name {
  font-weight: 700;
}

.leaderboard-meta {
  color: var(--muted);
  font-size: 0.92rem;
}

.leaderboard-empty {
  color: var(--muted);
  text-align: center;
  padding: 14px;
  border: 1px dashed #dbc7ad;
  border-radius: 14px;
}

@media (max-width: 960px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .board {
    width: min(100%, 680px);
  }
}

@media (max-width: 600px) {
  body {
    padding: 12px;
  }

  .app {
    padding: 16px;
    border-radius: 20px;
  }

  .panel,
  .board-wrap {
    padding: 14px;
  }

  .game-area {
    gap: 14px;
  }

  .inline-field,
  .panel-header {
    flex-direction: column;
    align-items: stretch;
  }

  .panel-actions {
    justify-content: stretch;
  }

  .panel-actions button {
    width: 100%;
  }

  .status-actions {
    justify-content: stretch;
  }

  .status-actions button {
    width: 100%;
    min-width: 0;
  }

  .replay-controls {
    gap: 8px;
  }

  .board {
    width: 100%;
    gap: 3px;
    padding: 6px;
    border-radius: 10px;
  }

  .board[data-size="5"],
  .board[data-size="6"] {
    gap: 2px;
    padding: 5px;
  }

  .tile-index {
    top: 2px;
    left: 2px;
    padding: 1px 3px;
    font-size: 0.52rem;
  }

  .leaderboard-panel {
    margin-top: 16px;
  }
}