.slideshow {
    height: 400px;
    object-fit: cover;
}

/* ===== 导航二级下拉（纯 CSS 悬停展开） ===== */
.navbar .navbar-nav .dropdown {
    position: relative;
}

.navbar .navbar-nav .dropdown-toggle {
    cursor: pointer;
}

/* 有子栏目时显示小箭头 */
.navbar .navbar-nav .dropdown-toggle .caret {
    display: inline-block;
    width: 0;
    height: 0;
    margin-left: 6px;
    vertical-align: middle;
    border-top: 5px solid currentColor;
    border-right: 5px solid transparent;
    border-left: 5px solid transparent;
    transition: transform .25s ease;
}

/* 下拉面板：默认隐藏，悬停展开 */
.navbar .navbar-nav .dropdown-menu {
    display: block;
    min-width: 180px;
    margin: 0;
    padding: 8px 0;
    border: 0;
    border-radius: 10px;
    background: #fff;
    box-shadow: 0 12px 32px rgba(0, 0, 0, .14);
    list-style: none;
    opacity: 0;
    visibility: hidden;
    transform: translateY(12px);
    transition: opacity .25s ease, transform .25s ease, visibility .25s ease;
}

.navbar .navbar-nav .dropdown:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.navbar .navbar-nav .dropdown:hover .dropdown-toggle .caret {
    transform: rotate(180deg);
}

/* 下拉项样式 */
.navbar .navbar-nav .dropdown-menu .dropdown-item {
    display: block;
    padding: 9px 22px;
    color: #333;
    font-size: 14px;
    line-height: 1.5;
    white-space: nowrap;
    text-decoration: none;
    transition: color .2s ease, background .2s ease, padding-left .2s ease;
}

.navbar .navbar-nav .dropdown-menu .dropdown-item:hover {
    color: #185FA5;
    background: #F0F6FC;
    padding-left: 28px;
}

/* 下拉项分隔线 */
.navbar .navbar-nav .dropdown-menu .dropdown-item + .dropdown-item {
    border-top: 1px solid #f2f2f2;
}

/* 移动端折叠时：二级菜单改为静态展示（点击导航条展开后直接可见，不悬浮） */
@media (max-width: 991.98px) {
    .navbar .navbar-nav .dropdown-menu {
        position: static;
        box-shadow: none;
        padding: 0 0 0 16px;
        opacity: 1;
        visibility: visible;
        transform: none;
        border-left: 2px solid #e9ecef;
        margin-bottom: 4px;
    }
}