/* ================================
   专业导航栏 - 支持Mega Menu
   ================================ */
.navbar {
    background: var(--bg-primary);
    border-bottom: 1px solid var(--border-light);
    position: fixed; /* 改为fixed以确保在所有浏览器中都能正确固定 */
    width: 100%; /* 确保宽度100% */
    left: 0; /* 确保左对齐 */
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(8px);
    transition: transform 0.3s ease-out, box-shadow 0.3s ease, opacity 0.3s ease;
    will-change: transform, opacity;
}

.navbar.scrolled {
    box-shadow: var(--shadow-md);
}

/* 导航栏隐藏效果 */
.navbar.navbar-hidden {
    transform: translateY(-100%);
    box-shadow: none;
    opacity: 0;
    pointer-events: none; /* 隐藏时禁用交互 */
}

.nav-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4) 0;
    position: relative;
}

.brand {
    font-size: var(--text-xl);
    font-weight: 700;
    color: var(--primary-brand);
    text-decoration: none;
    letter-spacing: -0.025em;
}

.nav-menu {
    display: flex;
    align-items: center;
    gap: var(--space-4);
    list-style: none;
    margin: 0;
    padding: 0;
}

.nav-item {
    position: relative;
}

.nav-link {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    font-size: var(--text-base);
    transition: color var(--transition-fast);
    position: relative;
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-4);
    border-radius: 6px;
}

.nav-link:hover {
    color: var(--primary-brand);
    background: rgba(10, 36, 99, 0.05);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -8px;
    left: 50%;
    transform: translateX(-50%);
    width: 20px;
    height: 2px;
    background: var(--primary-brand);
    border-radius: 1px;
}

.nav-icon {
    font-size: var(--text-sm);
    margin-right: var(--space-1);
    display: inline-block;
    vertical-align: middle;
}

.dropdown-arrow {
    font-size: var(--text-xs);
    transition: transform var(--transition-fast);
    opacity: 0.7;
}

.nav-item:hover .dropdown-arrow {
    transform: rotate(180deg);
}

/* ================================
   搜索框和导航操作区域
   ================================ */
.nav-actions {
    display: flex;
    align-items: center;
    gap: var(--space-4);
}

/* ================================
   Mega Menu 样式 - 玻璃形态学设计
   ================================ */
.mega-menu {
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    width: 900px;
    max-width: 90vw;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(20px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 16px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1), 0 4px 12px rgba(0, 0, 0, 0.05);
    opacity: 0;
    visibility: hidden;
    transform: translateX(-50%) translateY(-10px);
    transition: all var(--transition-normal);
    z-index: 1001;
    margin-top: var(--space-2);
}

.mega-menu-container {
    padding: var(--space-8);
}

.mega-menu-content {
    display: grid;
    grid-template-columns: repeat(3, 1fr) 300px;
    gap: var(--space-8);
}

.mega-menu-column {
    min-width: 0;
}

.mega-menu-title {
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--primary-brand);
    margin-bottom: var(--space-4);
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding-bottom: var(--space-2);
    border-bottom: 1px solid var(--border-light);
}

.title-icon {
    font-size: var(--text-lg);
}

.mega-menu-list {
    list-style: none;
    margin: 0;
    padding: 0;
}

.mega-menu-list li {
    margin-bottom: var(--space-1);
}

.mega-menu-link {
    display: block;
    color: var(--text-secondary);
    text-decoration: none;
    padding: var(--space-2) var(--space-3);
    border-radius: 6px;
    font-size: var(--text-sm);
    transition: all var(--transition-fast);
    position: relative;
}

.mega-menu-link:hover {
    background: rgba(10, 36, 99, 0.08);
    color: var(--primary-brand);
    transform: translateX(4px);
}

.mega-menu-link::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 0;
    height: 2px;
    background: var(--primary-brand);
    transition: width var(--transition-fast);
}

.mega-menu-link:hover::before {
    width: 3px;
}

/* ================================
   Mega Menu 特色推荐区域
   ================================ */
.mega-menu-featured {
    background: linear-gradient(135deg, rgba(10, 36, 99, 0.05), rgba(10, 36, 99, 0.02));
    border: 1px solid rgba(10, 36, 99, 0.1);
    border-radius: 12px;
    padding: var(--space-6);
}

.featured-title {
    font-size: var(--text-base);
    font-weight: 600;
    color: var(--primary-brand);
    margin-bottom: var(--space-4);
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.featured-articles {
    margin-bottom: var(--space-6);
}

.featured-article {
    display: flex;
    gap: var(--space-3);
    padding: var(--space-3);
    border-radius: 8px;
    transition: background var(--transition-fast);
    margin-bottom: var(--space-3);
}

.featured-article:hover {
    background: rgba(255, 255, 255, 0.5);
}

.article-thumb {
    width: 40px;
    height: 40px;
    background: var(--primary-brand);
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.thumb-icon {
    font-size: var(--text-lg);
    filter: grayscale(1) brightness(2);
}

.article-info {
    flex: 1;
    min-width: 0;
}

.article-title {
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--text-primary);
    margin: 0 0 var(--space-1) 0;
    line-height: 1.4;
}

.article-title a {
    color: var(--text-primary);
    text-decoration: none;
    transition: color var(--transition-fast);
    position: relative;
}

.article-title a:hover {
    color: var(--primary-brand);
}

.article-title a::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--primary-brand);
    transition: width var(--transition-fast);
}

.article-title a:hover::after {
    width: 100%;
}

.article-meta {
    font-size: var(--text-xs);
    color: var(--text-tertiary);
    margin: 0;
}

.mega-menu-cta {
    text-align: center;
}

.mega-menu-cta .cta-button {
    display: inline-block;
    background: var(--primary-brand);
    color: white;
    text-decoration: none;
    padding: var(--space-2) var(--space-4);
    border-radius: 6px;
    font-size: var(--text-sm);
    font-weight: 500;
    transition: all var(--transition-fast);
}

.mega-menu-cta .cta-button:hover {
    background: #0d47a1;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(10, 36, 99, 0.3);
}

/* ================================
   简化下拉菜单样式
   ================================ */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 220px;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(15px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all var(--transition-normal);
    z-index: 1001;
    margin-top: var(--space-2);
}

.dropdown-content {
    padding: var(--space-4);
}

.dropdown-link {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    color: var(--text-secondary);
    text-decoration: none;
    padding: var(--space-3);
    border-radius: 8px;
    font-size: var(--text-sm);
    transition: all var(--transition-fast);
    margin-bottom: var(--space-1);
}

.dropdown-link:hover {
    background: rgba(10, 36, 99, 0.08);
    color: var(--primary-brand);
}

.link-icon {
    font-size: var(--text-base);
    opacity: 0.8;
}

/* ================================
   菜单显示/隐藏控制
   ================================ */
.nav-item:hover .mega-menu,
.nav-item:hover .dropdown-menu {
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(0); /* Mega Menu */
}

.nav-item:hover .dropdown-menu {
    transform: translateY(0); /* 普通下拉菜单 */
}

/* ================================
   Mega Menu 遮罩层
   ================================ */
.mega-menu-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.1);
    opacity: 0;
    visibility: hidden;
    transition: all var(--transition-normal);
    z-index: 999;
    backdrop-filter: blur(2px);
}

.nav-item:hover ~ .mega-menu-overlay {
    opacity: 1;
    visibility: visible;
}

/* 移动端菜单按钮 */
.mobile-menu-btn {
    display: none; /* 默认隐藏 */
    background-color: rgba(240, 240, 240, 0.5);
    border: 1px solid var(--border-medium);
    color: var(--text-primary);
    width: 40px;
    height: 40px;
    border-radius: 6px;
    cursor: pointer;
    font-size: var(--text-lg);
    transition: all 0.3s ease;
    align-items: center;
    justify-content: center;
    z-index: 1001; /* 确保按钮在菜单上方 */
}

/* 防止菜单打开时页面滚动 */
body.menu-open {
    overflow: hidden;
    position: fixed;
    width: 100%;
    height: 100%;
}

body.mobile-menu-open .mobile-menu-btn {
    background-color: var(--primary-brand, #0A2463);
    color: white;
    border-color: var(--primary-brand, #0A2463);
    /* 增强按钮在浅色背景下的可见度 */
    box-shadow: 0 0 0 3px rgba(10, 36, 99, 0.3);
}

/* ================================
   高分辨率优化
   ================================ */
@media (min-width: 1600px) {
    .mega-menu {
        width: 1100px;
    }
    
    .mega-menu-content {
        grid-template-columns: repeat(3, 1fr) 350px;
        gap: var(--space-12);
    }
    
    .nav-link {
        font-size: var(--text-lg);
        padding: var(--space-4) var(--space-6);
    }
}

@media (min-width: 1920px) {
    .brand {
        font-size: var(--text-2xl);
    }
    
    .nav-link {
        font-size: var(--text-lg);
    }
    
    .nav-content {
        padding: var(--space-6) 0;
    }
}

/* ================================
   响应式适配
   ================================ */
@media (max-width: 1024px) {
    .mega-menu {
        width: 95vw;
    }
    
    .mega-menu-content {
        grid-template-columns: 1fr;
        gap: var(--space-6);
    }
    
    .mega-menu-featured {
        order: -1;
    }
    
    .search-input {
        width: 150px;
    }
    
    .search-input:focus {
        width: 200px;
    }
}

@media (max-width: 768px) {
    .mobile-menu-btn {
        display: flex; /* 移动端显示，使用flex布局以便居中内容 */
    }
    
    /* 隐藏导航链接激活状态的下划线 */
    .nav-link.active::after {
        display: none;
    }
    
    /* 隐藏Mega菜单中的特色推荐区域 */
    .mega-menu-featured {
        display: none;
    }
    
    .nav-menu {
        display: none;
        position: absolute;
        top: 100%;
        left: 0;
        width: 100%;
        /* 增加背景不透明度 */
        background-color: #FFFFFF;
        /* 添加额外的背景层，确保完全不透明 */
        backdrop-filter: blur(5px);
        /* 增强阴影效果 */
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
        /* 添加边框增强可见度 */
        border: 1px solid var(--border-medium);
        z-index: 100;
        padding: var(--space-4) 0;
        /* 确保菜单全宽显示 */
        max-width: 100%;
        margin: 0;
    }
    
    .nav-menu.active {
        display: block;
    }
    
    .nav-menu .menu-item {
        display: block;
        margin: 0;
        padding: var(--space-3) var(--space-6);
        /* 添加边框分隔菜单项 */
        border-bottom: 1px solid var(--border-light);
        /* 添加背景色增强可见度 */
        background-color: var(--surface-primary);
    }
    
    .nav-menu .menu-item:hover {
        background-color: var(--surface-secondary);
    }
    
    .nav-menu .menu-item:last-child {
        border-bottom: none;
    }
    
    .nav-menu .menu-item > a {
        display: block;
        font-weight: 500;
        color: var(--text-primary);
        /* 增加内边距使点击区域更大 */
        padding: var(--space-2) 0;
    }
    
    /* 移动端下拉菜单 */
    .nav-menu .dropdown-menu {
        position: static;
        box-shadow: none;
        display: none;
        padding-left: var(--space-6);
        background-color: var(--surface-secondary);
        /* 添加边框增强可见度 */
        border-top: 1px solid var(--border-light);
        border-bottom: 1px solid var(--border-light);
        /* 确保完全不透明 */
        backdrop-filter: blur(5px);
        /* 添加内边距 */
        padding: var(--space-2) var(--space-6);
        margin: var(--space-2) 0;
    }
    
    .nav-menu .dropdown-menu.active {
        display: block;
    }
    
    /* 移动端Mega菜单 */
    .nav-menu .mega-menu {
        position: relative;
        width: 100%;
        box-shadow: var(--shadow-md);
        padding: 0;
        background-color: var(--surface-secondary);
        /* 添加边框增强可见度 */
        border-top: 1px solid var(--border-light);
        border-bottom: 1px solid var(--border-light);
        /* 确保完全不透明 */
        backdrop-filter: blur(5px);
        display: none;
        margin: 0;
        left: 0;
        transform: none;
        max-width: 100%;
        z-index: 100;
        -webkit-overflow-scrolling: touch;
        overflow-y: auto;
        max-height: 80vh; /* 限制最大高度，避免内容超出屏幕 */
    }
    
    .nav-menu .mega-menu.active {
        display: block;
    }
    
    /* 优化Mega菜单内容布局 - 移动端列表样式 */
    .nav-menu .mega-menu .mega-menu-content {
        display: block;
        padding: 0;
        width: 100%;
        max-width: 100%;
        overflow-x: hidden; /* 防止水平溢出 */
    }
    
    /* 移动端Mega菜单列 */
    .nav-menu .mega-menu .mega-menu-column {
        margin-bottom: 0;
        padding: 0;
        background-color: var(--surface-secondary);
        border-radius: 0;
        border-bottom: 1px solid var(--border-light);
        width: 100%;
    }
    
    .nav-menu .mega-menu .mega-menu-column:last-child {
        border-bottom: none;
    }
    
    /* 移动端Mega菜单标题 */
    .nav-menu .mega-menu .mega-menu-column h4 {
        font-size: var(--text-md);
        margin: 0;
        padding: var(--space-3) var(--space-6);
        border-bottom: none;
        background-color: var(--surface-secondary);
        display: flex;
        align-items: center;
        justify-content: space-between;
        cursor: pointer;
        position: relative;
    }
    
    /* 添加展开/收起指示器 */
    .nav-menu .mega-menu .mega-menu-column h4:after {
        content: '+';
        font-size: var(--text-lg);
        font-weight: 300;
        color: var(--text-secondary);
        transition: transform 0.3s ease;
    }
    
    .nav-menu .mega-menu .mega-menu-column h4.active {
        background-color: var(--surface-secondary);
    }
    
    .nav-menu .mega-menu .mega-menu-column h4.active:after {
        content: '-';
    }
    
    /* 移动端Mega菜单列表 */
    .nav-menu .mega-menu .mega-menu-list {
        margin: 0;
        padding: 0;
        list-style: none;
        background-color: var(--surface-secondary);
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
        overflow-x: hidden;
    }
    
    .nav-menu .mega-menu .mega-menu-list li {
        margin: 0;
        border-bottom: 1px solid var(--border-light);
        width: 100%;
        position: relative;
    }
    
    .nav-menu .mega-menu .mega-menu-list li:last-child {
        border-bottom: none;
    }
    
    .nav-menu .mega-menu .mega-menu-list li a {
        display: block;
        padding: var(--space-3) var(--space-8);
        color: var(--text-primary);
        font-size: var(--text-sm);
        text-decoration: none;
        transition: all 0.2s ease;
        white-space: normal; /* 允许文本换行 */
        word-break: break-word; /* 在必要时断词 */
        overflow-wrap: break-word; /* 确保长单词也能换行 */
    }
    
    .nav-menu .mega-menu .mega-menu-list li a:hover,
    .nav-menu .mega-menu .mega-menu-list li a:focus {
        background-color: var(--surface-secondary);
        color: var(--text-accent);
        padding-left: calc(var(--space-8) + 5px);
    }
    
    /* 移动端特色推荐区域 */
    .nav-menu .mega-menu .mega-menu-featured {
        padding: 0;
        background-color: var(--surface-secondary);
        border-top: 1px solid var(--border-light);
    }
    
    .nav-menu .mega-menu .featured-articles {
        padding: var(--space-3) var(--space-6);
    }
    
    .nav-menu .mega-menu .featured-article {
        padding: var(--space-3) 0;
        border-bottom: 1px solid var(--border-light);
        display: flex;
        align-items: center;
        gap: var(--space-3);
    }
    
    .nav-menu .mega-menu .featured-article:last-child {
        border-bottom: none;
    }
    
    .nav-menu .mega-menu .featured-article img {
        width: 60px;
        height: 60px;
        object-fit: cover;
        border-radius: var(--radius-sm);
    }
    
    .nav-menu .mega-menu .featured-article .article-info {
        flex: 1;
    }
    
    .nav-menu .mega-menu .featured-article .article-title {
        font-size: var(--text-sm);
        font-weight: 500;
        margin: 0 0 var(--space-1);
        line-height: 1.3;
    }
    
    .nav-menu .mega-menu .featured-article .article-meta {
        font-size: var(--text-xs);
        color: var(--text-secondary);
        display: flex;
        gap: var(--space-2);
    }
    
    .nav-menu .mega-menu .view-all-link {
        display: block;
        text-align: center;
        padding: var(--space-3) 0;
        margin-top: var(--space-2);
        background-color: var(--surface-secondary);
        color: var(--text-accent);
        font-weight: 500;
        border-radius: var(--radius-sm);
        transition: all 0.2s ease;
    }
    
    .nav-menu .mega-menu .view-all-link:hover {
        background-color: var(--surface-hover);
    }
    
    .nav-menu .mega-menu .mega-menu-cta {
        padding: var(--space-4) var(--space-6);
        text-align: center;
        background-color: var(--surface-secondary);
        border-top: 1px solid var(--border-light);
    }
    
    .nav-menu .mega-menu .mega-menu-cta .btn {
        display: block;
        width: 100%;
        padding: var(--space-3) var(--space-4);
        background-color: var(--color-primary);
        color: var(--text-on-primary);
        border-radius: var(--radius-sm);
        font-weight: 500;
        text-align: center;
        transition: all 0.2s ease;
    }
    
    .nav-menu .mega-menu .mega-menu-cta .btn:hover {
        background-color: #0056b3;
        transform: translateY(-2px);
    }
    
    .nav-actions {
        gap: var(--space-2);
    }
    
    .search-box {
        display: none;
    }
    
    .nav-content {
        justify-content: space-between;
        padding: var(--space-4) var(--space-2);
    }
}