/* ============ 教师课件上传下载平台 - 全局样式 ============ */
:root {
  --brand: #3b82f6;
  --brand-dark: #2563eb;
  --bg-light: #f5f7fb;
}

body {
  background-color: var(--bg-light);
  font-family: "Microsoft YaHei", "PingFang SC", "Segoe UI", sans-serif;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.main-wrap { flex: 1; }

/* ---- 顶部导航（吸顶） ---- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1030;
  background: #fff;
  border-bottom: 1px solid rgba(0, 0, 0, .06);
}
.site-brand { display: inline-flex; align-items: center; }
.site-brand .brand-logo {
  height: 44px;
  width: auto;
  max-width: 180px;
  object-fit: contain;
}
.site-brand .brand-text {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: .5px;
  background: linear-gradient(120deg, #2563eb, #7c3aed);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  color: #2563eb;
}
@media (max-width: 768px) {
  .site-brand .brand-text { font-size: 1.1rem; }
  .site-brand .brand-logo { height: 36px; }
}

/* ---- 导航小屏适配 ----
   断点提高到 1200px（expand-xl）：<1200px 折叠为汉堡菜单，
   避免 992~1200px 区间导航全展开挤压成一排 */
.nav-search .nav-search-input { width: 220px; }
@media (max-width: 1199.98px) {
  .nav-search {
    width: 100%;
    margin: .5rem 0 .75rem !important;
  }
  .nav-search .nav-search-input {
    flex: 1 1 auto;
    width: auto;
    min-width: 0;
  }
}
.notice-bar { background: #fff8e1; font-size: .85rem; }
.dropdown-menu .sub-menu {
  list-style: none;
  padding-left: 1rem;
  margin: 0;
}
.avatar-placeholder {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--brand);
  color: #fff;
  font-size: .85rem;
}

/* ---- 卡片 ---- */
.card { border: none; border-radius: .75rem; box-shadow: 0 1px 4px rgba(0,0,0,.06); }
.card-hover { transition: transform .15s ease, box-shadow .15s ease; }
.card-hover:hover { transform: translateY(-4px); box-shadow: 0 8px 20px rgba(0,0,0,.12); }

/* ---- 课件卡片（小卡片） ---- */
.cw-card .cw-cover {
  height: 110px;
  background: #f8fafc;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.cw-card .cw-cover img { width: 100%; height: 100%; object-fit: contain; padding: 4px; }
.cw-card .cw-cover .type-icon {
  font-size: 1.6rem;
  color: var(--brand);
}
.cw-card .card-body { padding: .6rem .75rem; }
.cw-card .card-title { font-size: .85rem; margin-bottom: .25rem; line-height: 1.3; }
.cw-card .price { color: #f97316; font-weight: 700; font-size: .9rem; }
.cw-card .price.free { color: #16a34a; }
.cw-meta { font-size: .72rem; color: #6b7280; }

/* ---- 详情页 ---- */
.detail-cover {
  height: 260px;
  border-radius: .75rem;
  background: linear-gradient(135deg, #dbeafe, #eff6ff);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
.detail-cover img { width: 100%; height: 100%; object-fit: cover; }
.detail-cover .type-icon { font-size: 4rem; color: var(--brand); }
.price-tag { color: #f97316; font-size: 1.6rem; font-weight: 700; }
.comment-item { border-bottom: 1px dashed #e5e7eb; padding: .75rem 0; }

/* ---- 按钮 ---- */
.btn-brand { background: var(--brand); border-color: var(--brand); color: #fff; }
.btn-brand:hover { background: var(--brand-dark); border-color: var(--brand-dark); color: #fff; }

/* ---- 后台：侧边栏与顶栏固定，仅内容区滚动 ---- */
.admin-layout {
  height: 100vh;
  overflow: hidden;
}
.admin-sidebar {
  width: 220px;
  flex-shrink: 0;
  height: 100%;
  display: flex;
  flex-direction: column;
  background: #1f2937;
  color: #d1d5db;
  overflow: hidden;
}
.admin-sidebar .admin-nav {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
  overflow-x: hidden;
  /* Bootstrap 的 .nav 自带 flex-wrap:wrap，纵向放不下时会横向换列、溢出侧边栏，
     这里必须禁止换行，让超出部分走纵向滚动 */
  flex-wrap: nowrap;
  /* 深色侧边栏配深色滚动条，避免浅色滚动条突兀 */
  scrollbar-width: thin;
  scrollbar-color: #4b5563 transparent;
}
.admin-sidebar .admin-nav::-webkit-scrollbar { width: 6px; }
.admin-sidebar .admin-nav::-webkit-scrollbar-thumb { background: #4b5563; border-radius: 3px; }
.admin-sidebar .admin-nav::-webkit-scrollbar-track { background: transparent; }
/* 禁止菜单项被压扁：空间不足时应纵向滚动，而不是压缩每项高度 */
.admin-sidebar .admin-nav > * { flex-shrink: 0; }
.admin-main {
  flex: 1 1 auto;
  min-width: 0;
  height: 100%;
  display: flex;
  flex-direction: column;
}
.admin-topbar { flex: 0 0 auto; }
.admin-content {
  flex: 1 1 auto;
  min-height: 0;
  overflow-y: auto;
}
.admin-sidebar .nav-link { color: #d1d5db; border-radius: .4rem; margin-bottom: .15rem; }
.admin-sidebar .nav-link:hover { background: #374151; color: #fff; }
.admin-sidebar .nav-link.active { background: var(--brand); color: #fff; }
.admin-sidebar .brand { color: #fff; }

/* ---- 后台：可折叠的分组菜单 ---- */
.admin-sidebar .admin-group-toggle {
  color: #9ca3af;
  cursor: pointer;
  user-select: none;
  margin-top: .35rem;
}
.admin-sidebar .admin-group-toggle:hover { color: #e5e7eb; }
.admin-sidebar .menu-caret {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  opacity: .9;
  transition: transform .2s ease;
}
.admin-sidebar .menu-caret svg { display: block; width: 13px; height: 13px; }
.admin-sidebar .admin-group-toggle[aria-expanded="true"] .menu-caret { transform: rotate(180deg); }

/* ---- 表格 ---- */
.table th { white-space: nowrap; }
.page-link { color: var(--brand); }
.page-item.active .page-link { background: var(--brand); border-color: var(--brand); }

/* ---- Toast ---- */
.toast-container { z-index: 1080; }

/* ---- 登录/注册卡片 ---- */
.auth-card { max-width: 440px; margin: 3rem auto; }
.form-label { font-weight: 500; }

/* ---- 教师工作台 ---- */
.stat-card { border-radius: .75rem; color: #fff; }
.stat-card .num { font-size: 1.8rem; font-weight: 700; }
.stat-blue { background: linear-gradient(135deg, #3b82f6, #2563eb); }
.stat-green { background: linear-gradient(135deg, #10b981, #059669); }
.stat-orange { background: linear-gradient(135deg, #f59e0b, #d97706); }
.stat-purple { background: linear-gradient(135deg, #8b5cf6, #7c3aed); }

/* ---- 空状态 ---- */
.empty-tip { color: #9ca3af; text-align: center; padding: 3rem 0; }
.empty-tip i { font-size: 3rem; display: block; margin-bottom: .5rem; }

/* ---- 首页横幅 ---- */
.hero-banner {
  background: linear-gradient(120deg, #2563eb, #7c3aed);
  color: #fff;
  border-radius: 1rem;
  padding: 3rem 2rem;
}
.hero-banner h1 { font-weight: 700; }

/* ---- 富文本展示：段落首行缩进 2 字符 ---- */
.about-content p, .notice-content p, .ql-snow .ql-editor p {
  text-indent: 2em;
  margin-bottom: .8em;
}

/* 分类 mega menu 两列布局 */
.category-mega {
  padding: 0;
  border: none;
  box-shadow: 0 .5rem 1rem rgba(0,0,0,.15);
  border-radius: .5rem;
  overflow: hidden;
}
.category-mega .cat-grid {
  display: grid;
  grid-template-columns: repeat(3, 160px);
  gap: 0;
  max-height: 420px;
  overflow-y: auto;
}
.category-mega .cat-col {
  padding: 8px 0;
  border-right: 1px solid #f0f0f0;
}
.category-mega .cat-col:last-child { border-right: none; }
.category-mega .cat-parent {
  padding: 6px 16px;
  color: #1a73e8;
  font-size: 14px;
}
.category-mega .cat-child {
  padding: 4px 16px 4px 28px;
  font-size: 13px;
  color: #555;
}
.category-mega .cat-parent:hover,
.category-mega .cat-child:hover {
  background: #f5f8ff;
  color: #1a73e8;
}