/* 菜单展开容器 */
#mainNavbar.collapse.show {
    background-color: #fff !important;
    width: 100% !important;
    position: absolute; /* 如果你想菜单浮层 */
    top: 80px; /* 顶部距离为header高度 */
    left: 0;
    padding: 1rem 0;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
    z-index: 1040; /* 比header高1层 */
}

/* 菜单列表竖排且宽度100% */
#mainNavbar .navbar-nav {
    flex-direction: column !important;
    width: 100%;
}

/* 菜单项铺满宽度 */
#mainNavbar .navbar-nav .nav-item {
    width: 100%;
}

/* 菜单链接铺满，方便点击 */
#mainNavbar .navbar-nav .nav-link {
    width: 100%;
    padding: 12px 20px;
    color: #333 !important;
}

/* 鼠标悬停颜色 */
#mainNavbar .navbar-nav .nav-link:hover,
#mainNavbar .navbar-nav .nav-link:focus {
    background-color: #f8f9fa;
    color: #a61b29 !important;
}

#mainNavbar.collapse.show {
    background-color: #fff !important;
    z-index: 1050;
    position: absolute;
    top: 80px;
    left: 0;
    width: 100%;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    transition: none !important;
}

.banner {
    height: 280px !important;
}