/* 404 */
.error-page { display: flex; flex-direction: column; align-items: center; justify-content: center; min-height: 60vh; }
.error-page h1 { font-size: 80px; background: linear-gradient(135deg,var(--primary),#8b5cf6); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; line-height: 1; }
.error-page p { color: var(--gray-500); margin-bottom: 24px; font-size: 16px; }
.error-page .error-sub { font-size: 13px; color: var(--gray-400); margin-bottom: 4px; }

/* ===== 课程文字内容区 ===== */
.course-content {
  font-size: 15px;
  line-height: 1.9;
  color: var(--gray-700);
  max-width: 720px;
  margin: 0 auto;
}
.course-content h2 {
  font-size: 20px;
  font-weight: 700;
  color: var(--gray-900);
  margin: 28px 0 12px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--primary-light);
}
.course-content h3 {
  font-size: 17px;
  font-weight: 600;
  color: var(--gray-800);
  margin: 22px 0 10px;
}
.course-content strong { color: var(--gray-900); }
.course-content p { margin-bottom: 14px; }
.course-content ul, .course-content ol { margin: 10px 0 14px 24px; }
.course-content li { margin-bottom: 6px; line-height: 1.7; }
.course-content table {
  width: 100%; border-collapse: collapse; margin: 14px 0; font-size: 13px;
}
.course-content th {
  background: var(--primary); color: #fff; padding: 8px 12px; text-align: left; font-weight: 600;
}
.course-content td {
  padding: 8px 12px; border-bottom: 1px solid var(--gray-100);
}
.course-content hr {
  border: none; border-top: 1px solid var(--gray-200); margin: 24px 0;
}
.course-content blockquote {
  border-left: 3px solid var(--primary);
  background: var(--primary-light);
  padding: 12px 16px;
  margin: 14px 0;
  border-radius: 0 8px 8px 0;
  color: var(--gray-600);
  font-size: 14px;
}

/* ===== 侧栏子菜单 ===== */
.sidebar-nav .nav-group { display: flex; align-items: center; gap: 10px; padding: 10px 12px; color: rgba(255,255,255,0.7); border-radius: 6px; font-size: 14px; cursor: pointer; transition: all 0.15s; margin-bottom: 2px; }
.sidebar-nav .nav-group:hover { background: rgba(255,255,255,0.1); color: #fff; }
.sidebar-nav .nav-group .nav-arrow { margin-left: auto; font-size: 10px; transition: transform 0.2s; }
.sidebar-nav .nav-group.open .nav-arrow { transform: rotate(90deg); }
.sidebar-nav .sub-nav { display: none; padding-left: 8px; }
.sidebar-nav .sub-nav.open { display: block; }
.sidebar-nav .sub-nav a { padding-left: 32px !important; font-size: 13px; }

/* ===== 空状态 ===== */
.empty-state { text-align:center; padding:50px 20px; }
.empty-state .empty-icon { font-size:48px; margin-bottom:12px; }
.empty-state h3 { font-size:16px; color:var(--gray-600); margin-bottom:6px; }
.empty-state p { font-size:13px; color:var(--gray-400); margin-bottom:16px; max-width:400px; margin-left:auto; margin-right:auto; }

/* ===== 卡片 hover 微提升 ===== */
.card { transition: box-shadow 0.2s; }
.card:hover { box-shadow: 0 2px 8px rgba(0,0,0,0.1); }

/* ===== 统计卡片 hover ===== */
.stat-card { transition: transform 0.15s, box-shadow 0.2s; }
.stat-card:hover { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(0,0,0,0.1); }

/* ===== 按钮微调 ===== */
.btn { transition: all 0.15s; }
.btn:active { transform: scale(0.97); }

/* ===== Toast 改进 ===== */
.toast { max-width: 400px; word-break: break-word; }

/* ===== 表格行悬停 ===== */
tr { transition: background 0.1s; }

/* ===== 滚动条美观 ===== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--gray-300); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--gray-400); }

/* ===== 输入框聚焦 ===== */
.form-input:focus, .form-select:focus, .form-textarea:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-light); }

/* ===== 路径百分比条 ===== */
.path-bar-wrap { display:flex; gap:16px; flex-wrap:wrap; }
.path-bar-item { flex:1; min-width:120px; text-align:center; }
.path-bar-label { font-size:12px; color:var(--gray-500); margin-bottom:4px; }
.path-bar { height:6px; background:var(--gray-200); border-radius:3px; overflow:hidden; }
.path-bar-fill { height:100%; background:var(--primary); border-radius:3px; transition:width 0.5s; }

/* ===== 下拉/弹窗动画 ===== */
.modal-overlay { animation: fadeIn 0.15s; }
.modal { animation: slideUp 0.2s; }
@keyframes fadeIn { from { opacity:0; } to { opacity:1; } }
@keyframes slideUp { from { transform:translateY(20px);opacity:0; } to { transform:translateY(0);opacity:1; } }