/* 平板友好基础样式 */
html, body { height: 100%; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, 'Noto Sans', 'PingFang SC', 'Microsoft Yahei', sans-serif;
  background: #f7f7f7;
  color: #222;
}

.app {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2rem 1rem;
}

.title {
  font-size: 1.5rem;
  text-align: center;
  margin: 0 0 1rem;
}

/* 3x3 网格，只用5格位置形成T字形 */
.workspace {
  display: flex;
  align-items: flex-start;
  gap: 2rem;
}

.grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  justify-items: stretch;
  align-items: stretch;
  width: clamp(360px, 60vw, 720px);
}

/* 单元格通用样式 */
.cell {
  background: #fff;
  border-radius: 16px;
  border: 3px solid #ddd;
  box-shadow: 0 2px 6px rgba(0,0,0,0.06);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  user-select: none;
  aspect-ratio: 1 / 1;
}

.cell .label {
  font-weight: 700;
  font-size: 2rem;
  color: #222;
  opacity: 0.8;
}

/* T字形具体坐标定位 */
#r1c1 { grid-column: 1; grid-row: 1; }
#r1c2 { grid-column: 2; grid-row: 1; }
#r1c3 { grid-column: 3; grid-row: 1; }
#r2c2 { grid-column: 2; grid-row: 2; }
#r3c2 { grid-column: 2; grid-row: 3; }

/* 颜色样式：使用高对比度，内部标签显示首字母辅助辨识 */
.red    { background: #e74c3c; border-color: #c0392b; }
.yellow { background: #f1c40f; border-color: #d4ac0d; }
.blue   { background: #3498db; border-color: #2e86c1; }
.red .label, .yellow .label, .blue .label { color: rgba(255,255,255,0.92); }

/* 隐藏态：留空白并提示占位 */
.hidden {
  background: #fff;
  border-style: dashed;
  border-color: #bbb;
}
.hidden .label { color: #bbb; }

/* 侧栏与按钮样式：右侧排列，触控友好 */
.sidebar {
  width: clamp(240px, 24vw, 320px);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.controls {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.rules {
  background: #fff;
  border-radius: 12px;
  border: 2px solid #e0e0e0;
  padding: 0.8rem 1rem;
  font-size: 0.9rem;
  color: #555;
}
.rules strong {
  display: block;
  margin-bottom: 0.4rem;
}
.rules ul {
  margin: 0;
  padding-left: 1.2rem;
}
.rules li {
  line-height: 1.7;
}

.btn {
  font-size: 1.125rem;
  padding: 1rem 1.5rem;
  border-radius: 12px;
  border: 2px solid #333;
  background: #333;
  color: #fff;
  min-width: 200px;
  width: 100%;
}
.btn.secondary {
  border-color: #666;
  background: #666;
}
.btn:active { transform: scale(0.98); }
.btn:focus { outline: 4px solid rgba(0,0,0,0.2); }

/* 各按钮活泼配色 */
#btnNext {
  background: #2ecc71;
  border-color: #27ae60;
}
#btnAnswer {
  background: #e67e22;
  border-color: #d35400;
}
#btnFullscreen {
  background: #3b82f6;
  border-color: #2563eb;
}

#btnNext:hover { background: #27ae60; }
#btnAnswer:hover { background: #d35400; }
#btnFullscreen:hover { background: #2563eb; }

/* 响应式：在小屏时增加网格高度以便触控 */
@media (max-width: 768px) {
  .workspace { flex-direction: column; }
  .grid { width: 100%; }
  .sidebar { width: 100%; }
}

body.is-fullscreen { background: #fff; }
.app:fullscreen {
  background: #fff;
  max-width: none;
  width: 100vw;
  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.app:fullscreen .workspace {
  justify-content: center;
}
.app:-webkit-full-screen {
  background: #fff;
  max-width: none;
  width: 100vw;
  height: 100vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
}
.app:-webkit-full-screen .workspace {
  justify-content: center;
}