/* ============ 整体布局 ============ */
#app {
  height: 100vh;
  display: flex;
  flex-direction: column;
}

.main-layout {
  flex: 1;
  display: flex;
  min-height: 0;
  gap: 14px;
  padding: 14px 16px 16px;
}

.side-panel {
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  min-height: 0;
  overflow: hidden;
}

.side-left  { width: 274px; flex-shrink: 0; transition: width .22s ease; }
.side-left.collapsed { width: 46px; }
.side-left.collapsed .panel-body,
.side-left.collapsed .panel-foot { display: none; }
.side-left.collapsed .panel-head {
  flex-direction: column; align-items: center;
  padding: 14px 4px; gap: 12px;
}
.side-left.collapsed .panel-head h3 { writing-mode: vertical-rl; letter-spacing: 6px; font-size: 12px; }
/* 折叠时隐藏辅助按钮，仅保留展开按钮（»），避免超出窄条宽度 */
.side-left.collapsed .panel-head .btn-ghost:not(.rules-toggle) { display: none; }
/* 折叠/展开按钮：两种状态同尺寸的方形按钮 */
.side-left .rules-toggle {
  width: 28px; height: 28px; padding: 0; font-size: 15px;
  display: inline-flex; align-items: center; justify-content: center;
  border: 1px solid var(--border); border-radius: 7px;
  flex-shrink: 0;
}
.side-left .rules-toggle:hover { border-color: var(--primary); color: var(--primary); }
.side-right { width: 280px; flex-shrink: 0; }

.classroom-wrap {
  flex: 1;
  min-width: 0;
  background: var(--bg-panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 16px 18px 12px;
  gap: 16px;
  overflow: auto;
}

/* 响应式：窄屏时侧栏折叠为可滚动堆叠 */
@media (max-width: 1080px) {
  body { overflow: auto; }
  #app { height: auto; min-height: 100vh; }
  .main-layout { flex-direction: column; }
  .side-left, .side-right { width: 100%; max-height: 380px; }
}