:root {
  color-scheme: light;
  --bg-1: #f2e2c2;
  --bg-2: #c88852;
  --bg-3: #8f5730;
  --ink: #2b1a10;
  --ink-soft: #4d3728;
  --accent: #b33f2e;
  --panel: #fbf5e9;
  --panel-edge: #d5b591;
  --shadow: rgba(27, 17, 11, 0.25);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Spectral", "Baskerville", "Georgia", serif;
  color: var(--ink);
  background: radial-gradient(circle at top, #fdf7ea, var(--bg-1) 40%, var(--bg-2) 75%, var(--bg-3));
  display: flex;
  justify-content: center;
  padding: 32px 20px 64px;
  position: relative;
  overflow-x: hidden;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(circle at 20% 20%, rgba(255, 255, 255, 0.35), transparent 50%),
    radial-gradient(circle at 80% 30%, rgba(255, 229, 180, 0.4), transparent 55%),
    repeating-linear-gradient(135deg, rgba(0, 0, 0, 0.03) 0 2px, transparent 2px 8px);
  opacity: 0.6;
  pointer-events: none;
  z-index: -1;
}

.page {
  width: min(1000px, 100%);
  display: grid;
  gap: 28px;
  animation: rise 0.8s ease-out;
}

.hero {
  text-align: left;
  display: grid;
  gap: 10px;
}

.eyebrow {
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  text-transform: uppercase;
  letter-spacing: 0.3em;
  font-size: 12px;
  color: var(--accent);
  margin: 0;
}

h1 {
  font-size: clamp(36px, 6vw, 56px);
  margin: 0;
  line-height: 1;
}

.subtitle {
  margin: 0;
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  font-size: 16px;
  color: var(--ink-soft);
}

.board-card {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 0.8fr);
  gap: 24px;
  align-items: start;
}

.board-wrap {
  background: linear-gradient(135deg, rgba(255, 255, 255, 0.3), rgba(255, 255, 255, 0));
  border-radius: 18px;
  padding: 18px;
  border: 1px solid rgba(255, 255, 255, 0.6);
  box-shadow: 0 18px 40px var(--shadow);
}

canvas {
  width: 100%;
  height: auto;
  border-radius: 12px;
  border: 2px solid #8b5d34;
  display: block;
  background: #d9b37a;
  touch-action: none;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--panel-edge);
  border-radius: 18px;
  padding: 24px;
  display: grid;
  gap: 16px;
  box-shadow: 0 12px 30px rgba(84, 54, 32, 0.2);
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  animation: fadeIn 0.9s ease-out;
}

.status {
  font-size: 22px;
  font-weight: 600;
}

.controls {
  display: flex;
  gap: 12px;
}

button {
  border: none;
  background: var(--accent);
  color: #fff6e9;
  padding: 12px 18px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.05em;
  cursor: pointer;
  box-shadow: 0 10px 18px rgba(179, 63, 46, 0.25);
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

button:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 22px rgba(179, 63, 46, 0.3);
}

.legend {
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
}

.chip {
  padding: 6px 12px;
  border-radius: 999px;
  font-size: 13px;
  border: 1px solid rgba(0, 0, 0, 0.08);
}

.chip.black {
  background: #1a1a1a;
  color: #f8e9d2;
}

.chip.white {
  background: #ffffff;
  color: #4b3323;
}

.hint {
  margin: 0;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.5;
}

@keyframes rise {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 860px) {
  .board-card {
    grid-template-columns: 1fr;
  }

  .panel {
    order: -1;
  }
}

@media (max-width: 600px) {
  body {
    padding: 24px 16px 48px;
  }

  .board-wrap {
    padding: 12px;
  }

  .panel {
    padding: 20px;
  }
}

/* 開始畫面樣式 */
.start-screen {
  position: fixed;
  inset: 0;
  background: rgba(43, 26, 16, 0.85);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  animation: fadeIn 0.4s ease-out;
}

.start-screen.hidden {
  display: none;
}

.start-card {
  background: var(--panel);
  border: 1px solid var(--panel-edge);
  border-radius: 24px;
  padding: 40px 48px;
  text-align: center;
  box-shadow: 0 24px 60px rgba(27, 17, 11, 0.5);
  animation: rise 0.5s ease-out;
  max-width: 400px;
  width: 90%;
}

.start-card h2 {
  font-size: 42px;
  margin: 0 0 8px;
  color: var(--ink);
}

.start-subtitle {
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  font-size: 16px;
  color: var(--ink-soft);
  margin: 0 0 28px;
}

.mode-selection {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.mode-selection.hidden {
  display: none;
}

.mode-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  width: 100%;
  padding: 18px 24px;
  background: var(--accent);
  border: none;
  border-radius: 14px;
  color: #fff6e9;
  font-size: 18px;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  box-shadow: 0 8px 20px rgba(179, 63, 46, 0.3);
}

.mode-btn:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(179, 63, 46, 0.4);
}

.mode-icon {
  font-size: 24px;
}

.mode-label {
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
}

.difficulty-selection {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.difficulty-selection.hidden {
  display: none;
}

.difficulty-title {
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  font-size: 16px;
  color: var(--ink-soft);
  margin: 0 0 8px;
}

.difficulty-buttons {
  display: flex;
  gap: 12px;
  justify-content: center;
}

.difficulty-btn {
  flex: 1;
  padding: 14px 16px;
  background: var(--accent);
  border: none;
  border-radius: 12px;
  color: #fff6e9;
  font-size: 15px;
  font-weight: 600;
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  cursor: pointer;
  transition: transform 0.2s ease, box-shadow 0.2s ease, background 0.2s ease;
  box-shadow: 0 6px 16px rgba(179, 63, 46, 0.25);
}

.difficulty-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 22px rgba(179, 63, 46, 0.35);
}

.difficulty-btn[data-difficulty="easy"] {
  background: #5a9e5a;
  box-shadow: 0 6px 16px rgba(90, 158, 90, 0.3);
}

.difficulty-btn[data-difficulty="easy"]:hover {
  box-shadow: 0 10px 22px rgba(90, 158, 90, 0.4);
}

.difficulty-btn[data-difficulty="medium"] {
  background: #d4a03a;
  box-shadow: 0 6px 16px rgba(212, 160, 58, 0.3);
}

.difficulty-btn[data-difficulty="medium"]:hover {
  box-shadow: 0 10px 22px rgba(212, 160, 58, 0.4);
}

.difficulty-btn[data-difficulty="hard"] {
  background: #c44d3a;
  box-shadow: 0 6px 16px rgba(196, 77, 58, 0.3);
}

.difficulty-btn[data-difficulty="hard"]:hover {
  box-shadow: 0 10px 22px rgba(196, 77, 58, 0.4);
}

.back-btn {
  margin-top: 8px;
  padding: 10px 20px;
  background: transparent;
  border: 2px solid var(--ink-soft);
  border-radius: 999px;
  color: var(--ink-soft);
  font-size: 14px;
  font-weight: 600;
  font-family: "Space Grotesk", "Trebuchet MS", "Gill Sans", sans-serif;
  cursor: pointer;
  transition: background 0.2s ease, color 0.2s ease;
  box-shadow: none;
}

.back-btn:hover {
  background: var(--ink-soft);
  color: var(--panel);
  transform: none;
  box-shadow: none;
}