/* ==========================================================================
   GaoShu-Review Common Page Layouts & Module Utilities
   ========================================================================== */

/* 通用页头与栅格 */
.page-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.page-title {
  font-size: var(--fs-24);
  font-weight: 700;
  color: var(--c-text);
  margin-bottom: 4px;
}

.page-subtitle {
  font-size: var(--fs-14);
  color: var(--c-text-2);
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.stack-lg {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.stack-md {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

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

/* 仪表盘与指标卡 */
.stat-kpi-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 16px 18px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.stat-kpi-label {
  font-size: var(--fs-12);
  color: var(--c-text-2);
  font-weight: 600;
}

.stat-kpi-value {
  font-size: var(--fs-24);
  font-weight: 700;
  color: var(--c-text);
  line-height: 1.25;
}

/* 知识点模块左右树布局 */
.knowledge-shell {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

.knowledge-tree-panel {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 14px;
  box-shadow: var(--shadow);
  max-height: calc(100vh - 104px);
  overflow-y: auto;
  position: sticky;
  top: 76px;
}

/* 练习与测验答题面板 */
.question-panel {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: 24px;
  box-shadow: var(--shadow);
}

.question-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  flex-wrap: wrap;
  margin-bottom: 12px;
}

.question-stem {
  font-size: 1.06rem;
  line-height: 1.85;
  color: var(--c-text);
  margin: 16px 0;
  overflow-x: auto;
}

.solution-panel {
  margin-top: 18px;
  padding: 18px 20px;
  border-radius: var(--radius);
  border: 1px solid var(--c-border);
  background: var(--c-bg);
}

.solution-step {
  padding: 10px 12px;
  border-left: 3px solid var(--c-primary);
  background: var(--c-surface);
  border-radius: 0 8px 8px 0;
  margin-bottom: 8px;
}

/* 模拟测验固定头与题号矩阵 */
.exam-workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 260px;
  gap: 20px;
  align-items: start;
}

.exam-timer {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 999px;
  background: var(--c-surface-2);
  color: var(--c-text);
}

.exam-timer.is-urgent {
  background: var(--c-danger-weak);
  color: var(--c-danger);
}

.q-nav-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 8px;
}

.q-nav-btn {
  height: 34px;
  border-radius: 6px;
  border: 1px solid var(--c-border);
  background: var(--c-surface);
  color: var(--c-text);
  font-size: var(--fs-12);
  font-weight: 600;
  cursor: pointer;
}

.q-nav-btn.is-answered {
  background: var(--c-primary-weak);
  border-color: var(--c-primary);
  color: var(--c-primary);
}

.q-nav-btn.is-flagged {
  border-color: var(--c-warning);
  box-shadow: inset 0 0 0 1px var(--c-warning);
}

.q-nav-btn.is-current {
  background: var(--c-primary);
  border-color: var(--c-primary);
  color: #ffffff;
}

/* 可视化演示：桌面左画布右控制面板，窄屏上下排布 */
.demo-split,
.demo-workspace {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 320px;
  gap: 18px;
  align-items: start;
}

.demo-canvas-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 12px;
  box-shadow: var(--shadow);
  overflow: hidden;
}

.demo-controls-card {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.demo-readout {
  background: var(--c-bg);
  border: 1px solid var(--c-border);
  border-radius: 8px;
  padding: 12px;
  font-size: var(--fs-14);
  line-height: 1.65;
}

/* 错题本筛选条与标签 */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: 14px 16px;
  margin-bottom: 16px;
}

/* 空状态 */
.empty-state {
  text-align: center;
  padding: 40px 20px;
  color: var(--c-text-2);
}

/* 响应式适配 */
@media (max-width: 1023px) {
  .grid-4 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .exam-workspace,
  .demo-split,
  .demo-workspace {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 767px) {
  .grid-2,
  .grid-3,
  .grid-4,
  .knowledge-shell {
    grid-template-columns: 1fr;
  }

  .knowledge-tree-panel {
    position: static;
    max-height: 300px;
  }

  .question-panel {
    padding: 16px;
  }
}