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

/* 导航下拉菜单样式 */
.navbar-nav .nav-item.dropdown {
    position: relative;
}

.navbar-nav .nav-item.dropdown > .nav-link {
    cursor: pointer;
}

/* 去掉 Bootstrap 默认的 dropdown-toggle 倒三角 */
.navbar-nav .nav-item.dropdown > .nav-link::after {
    display: none !important;
}

/* 下拉菜单容器 */
.navbar-nav .dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 180px;
    background: #fff;
    border: 1px solid #dee2e6;
    border-radius: 4px;
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.175);
    padding: 8px 0;
    z-index: 1000;
    margin-top: 0;
}

/* 桌面端：鼠标悬停在整个菜单项上显示下拉菜单 */
@media (min-width: 992px) {
    .navbar-nav .nav-item.dropdown:hover > .dropdown-menu {
        display: block;
    }
}

/* 下拉菜单项 */
.navbar-nav .dropdown-menu .dropdown-item {
    display: block;
    padding: 8px 20px;
    clear: both;
    font-weight: 400;
    color: #212529;
    text-align: inherit;
    white-space: nowrap;
    background: 0 0;
    border: 0;
    transition: background-color 0.3s;
}

.navbar-nav .dropdown-menu .dropdown-item a {
    color: #212529;
    text-decoration: none;
    display: block;
}

.navbar-nav .dropdown-menu .dropdown-item:hover {
    background-color: #f8f9fa;
}

.navbar-nav .dropdown-menu .dropdown-item.active {
    background-color: #e9ecef;
}

.navbar-nav .dropdown-menu .dropdown-item.active a {
    color: #007bff;
    font-weight: 500;
}

/* ========== 三栏顶栏样式 ========== */

/* 三栏头部容器 */
#triple-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    z-index: 1030;
}

/* 第一栏：欢迎栏 */
.welcome-bar {
    background-color: #333333;
    color: #ffffff;
    height: 36px;
    display: flex;
    align-items: center;
    font-size: 13px;
}

.welcome-bar .container {
    height: 100%;
}

.welcome-bar .row {
    align-items: center;
    height: 100%;
}

.welcome-text {
    padding: 0;
    line-height: 36px;
}

.contact-link {
    color: #ffffff;
    text-decoration: none;
    line-height: 36px;
    transition: color 0.3s;
}

.contact-link:hover {
    color: #27a8e1;
}

/* 第二栏：品牌信息栏 */
.brand-info-bar {
    background-color: #ffffff;
    min-height: 90px;
    padding: 15px 0;
    border-bottom: 1px solid #e8e8e8;
}

.brand-logo img {
    height: 60px;
    width: auto;
    object-fit: contain;
}

.company-service-line1 {
    font-size: 16px;
    font-weight: 500;
    color: #333333;
    line-height: 1.4;
}

.company-service-line2 {
    font-size: 14px;
    color: #666666;
    line-height: 1.4;
    margin-top: 3px;
}

.brand-contact {
    text-align: right;
}

.contact-phone {
    font-size: 16px;
    font-weight: bold;
    color: #27a8e1;
    margin-bottom: 5px;
}

.contact-phone i,
.contact-qq i {
    margin-right: 5px;
}

.contact-qq {
    font-size: 14px;
    color: #666666;
}

/* 第三栏：主菜单栏 */
.main-menu {
    background-color: #ffffff !important;
    min-height: 50px;
    border-top: none;
    border-bottom: 1px solid #e8e8e8;
}

/* 导航菜单居中 */
.main-menu .navbar-nav {
    margin: 0 auto;
}

.main-menu .nav-link {
    font-size: 15px;
    color: #333333 !important;
    padding: 12px 20px !important;
    font-weight: 500;
    transition: color 0.3s, border-bottom 0.3s;
    border-bottom: 2px solid transparent;
    position: relative;
}

.main-menu .nav-link:hover {
    color: #27a8e1 !important;
}

/* 当前页菜单项高亮 */
.main-menu .nav-item.active .nav-link {
    color: #27a8e1 !important;
    border-bottom-color: #27a8e1;
}

/* 下拉菜单样式优化 */
.main-menu .dropdown-menu {
    border: none;
    border-radius: 0 0 4px 4px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
    padding: 8px 0;
    margin-top: 0;
}

.main-menu .dropdown-item {
    padding: 10px 20px;
    font-size: 14px;
    color: #333333;
    transition: all 0.3s;
}

.main-menu .dropdown-item:hover {
    background-color: #f8f9fa;
    color: #27a8e1;
    padding-left: 25px;
}

/* 占位容器 */
.header-placeholder {
    height: 176px; /* 36 + 90 + 50 */
}

/* 移动端认证按钮 */
.mobile-auth-buttons {
    border-top: 1px solid #dee2e6;
    padding-top: 15px;
    margin-top: 15px !important;
}

.mobile-auth-buttons .btn {
    margin-bottom: 10px;
}

/* ========== 响应式设计 ========== */

/* 桌面端（≥992px）- 完整显示 */
@media (min-width: 992px) {
    .brand-info-bar {
        min-height: 90px;
    }

    .brand-logo img {
        height: 60px;
    }

    .company-name {
        font-size: 20px;
    }

    .company-service {
        font-size: 14px;
    }

    .contact-phone {
        font-size: 16px;
    }

    .contact-qq {
        font-size: 14px;
    }

    .header-placeholder {
        height: 176px; /* 36 + 90 + 50 */
    }
}

/* 平板端（768px-991px）- 简化显示 */
@media (max-width: 991.98px) and (min-width: 768px) {
    .brand-info-bar {
        min-height: 80px;
        padding: 12px 0;
    }

    .brand-logo img {
        height: 50px;
    }

    .company-name {
        font-size: 18px;
    }

    .company-service {
        font-size: 13px;
    }

    .contact-phone {
        font-size: 14px;
    }

    .contact-qq {
        font-size: 13px;
    }

    .header-placeholder {
        height: 166px;
    }
}

/* 移动端（577px-767px）- 进一步简化 */
@media (max-width: 767.98px) and (min-width: 577px) {
    .welcome-text {
        font-size: 12px;
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
    }

    .brand-info-bar {
        min-height: 70px;
        padding: 10px 0;
    }

    .brand-logo img {
        height: 45px;
    }

    .company-name {
        font-size: 16px;
    }

    .company-service {
        display: none;
    }

    .brand-contact {
        text-align: left;
    }

    .contact-qq {
        display: none;
    }

    .contact-phone {
        font-size: 14px;
    }

    .header-placeholder {
        height: 156px;
    }
}

/* 超小屏幕（≤576px）- 垂直堆叠 */
@media (max-width: 576.98px) {
    .welcome-text {
        font-size: 12px;
        overflow: hidden;
        text-overflow: ellipsis;
        white-space: nowrap;
        max-width: 200px;
    }

    .contact-link span {
        display: none;
    }

    .brand-info-bar {
        min-height: auto;
        padding: 10px 0;
    }

    .brand-info-bar .row {
        flex-direction: column;
        text-align: center;
    }

    .brand-logo {
        margin-bottom: 10px;
    }

    .brand-logo img {
        height: 40px;
    }

    .company-name {
        font-size: 15px;
        text-align: center;
    }

    .company-service {
        display: none;
    }

    .brand-contact {
        text-align: center;
        margin-top: 10px;
    }

    .contact-phone {
        font-size: 14px;
    }

    .contact-qq {
        display: none;
    }

    .header-placeholder {
        height: 150px;
    }

    .main-menu .nav-link {
        font-size: 14px;
        padding: 10px 15px !important;
    }

    /* 移动端下拉菜单样式 */
    .main-menu .dropdown-menu {
        position: static;
        display: none;
        box-shadow: none;
        border: none;
        background-color: #f8f9fa;
        padding-left: 15px;
    }

    .main-menu .dropdown.show .dropdown-menu {
        display: block;
    }

    .main-menu .dropdown-item {
        padding: 8px 15px;
        border-left: 2px solid #27a8e1;
        margin-left: 10px;
    }

    .main-menu .dropdown-item:hover {
        padding-left: 15px;
        background-color: #e9ecef;
    }
}

/* 移动端菜单展开时 */
@media (max-width: 991.98px) {
    .main-menu .navbar-collapse {
        background-color: #ffffff;
        border-top: 1px solid #dee2e6;
        max-height: calc(100vh - 176px);
        overflow-y: auto;
    }

    .main-menu .navbar-nav {
        width: 100%;
        padding: 10px 0;
    }

    .main-menu .nav-item {
        border-bottom: 1px solid #f0f0f0;
    }

    .main-menu .nav-link {
        border-bottom: none !important;
    }
}

/* 滚动时导航栏效果 */
.main-menu.shadow-on-scroll {
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}