/* Header样式 */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    transition: all 0.3s ease;
}

.header.scrolled {
    backdrop-filter: blur(20px);
    background: rgba(255, 255, 255, 0.95);
    box-shadow: var(--shadow-soft);
}

.header.hidden {
    transform: translateY(-100%);
}

/* 公告栏 */
.header-announcement {
    background: linear-gradient(135deg, var(--primary-blue), var(--primary-purple));
    color: var(--white);
    padding: 4px 0;
    overflow: hidden;
}

.announcement-slider {
    position: relative;
    height: 20px;
}

.announcement-item {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--spacing-sm);
    opacity: 0;
    transform: translateY(20px);
    transition: all 0.5s ease;
}

.announcement-item.active {
    opacity: 1;
    transform: translateY(0);
}

.announcement-item i {
    font-size: 14px;
}

.announcement-item span {
    font-size: 14px;
    font-weight: 400;
}

.announcement-link {
    color: var(--white);
    text-decoration: underline;
    font-weight: 500;
    font-size: 14px;
    transition: opacity 0.3s ease;
}

.announcement-link:hover {
    opacity: 0.8;
}

/* 导航栏 */
.navbar {
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(20px);
    padding: 0;
    border-bottom: 1px solid var(--border-light);
}

.navbar-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-sm) 0;
}

.navbar-brand .logo {
    height: 32px;
    width: auto;
    border-radius: var(--radius-sm);
}

/* 导航菜单 */
.navbar-menu {
    display: flex;
    align-items: center;
}

.navbar-nav {
    display: flex;
    list-style: none;
    margin: 0;
    padding: 0;
    gap: var(--spacing-lg);
}

.nav-item {
    position: relative;
}

.nav-link {
    display: flex;
    align-items: center;
    gap: var(--spacing-xs);
    padding: var(--spacing-sm) 0;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
    font-size: 16px;
    transition: all 0.3s ease;
    position: relative;
}

.nav-link:hover,
.nav-link.active {
    color: var(--primary-blue);
}

.nav-link.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(135deg, var(--primary-blue), var(--primary-purple));
    border-radius: 1px;
}

.nav-link i {
    font-size: 12px;
    transition: transform 0.3s ease;
}

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

/* 下拉菜单 */
.dropdown-menu {
    position: absolute;
    top: 100%;
    left: 0;
    min-width: 200px;
    background: var(--white);
    border-radius: var(--radius-md);
    box-shadow: var(--shadow-medium);
    padding: var(--spacing-sm) 0;
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: all 0.3s ease;
    border: 1px solid var(--border-light);
}

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

.dropdown-item {
    display: block;
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--text-primary);
    text-decoration: none;
    font-size: 14px;
    transition: all 0.3s ease;
}

.dropdown-item:hover {
    background: var(--light-gray);
    color: var(--primary-blue);
}

/* 导航栏操作按钮 */
.navbar-actions {
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}

/* 移动端菜单按钮 */
.mobile-menu-toggle {
    display: none;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
}

.mobile-menu-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-primary);
    border-radius: 1px;
    transition: all 0.3s ease;
}

.mobile-menu-toggle.active span:nth-child(1) {
    transform: rotate(45deg) translate(6px, 6px);
}

.mobile-menu-toggle.active span:nth-child(2) {
    opacity: 0;
}

.mobile-menu-toggle.active span:nth-child(3) {
    transform: rotate(-45deg) translate(6px, -6px);
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header-announcement {
        padding: 6px 0;
    }
    
    .announcement-item {
        height: 20px;
    }
    
    .announcement-item span,
    .announcement-link {
        font-size: 12px;
    }
    
    .navbar-content {
        padding: var(--spacing-sm) 0;
    }
    
    .navbar-brand .logo {
        height: 32px;
    }
    
    .navbar-menu {
        position: absolute;
        top: 100%;
        left: 0;
        right: 0;
        background: var(--white);
        border-top: 1px solid var(--border-light);
        box-shadow: var(--shadow-medium);
        opacity: 0;
        visibility: hidden;
        transform: translateY(-20px);
        transition: all 0.3s ease;
    }
    
    .navbar-menu.active {
        opacity: 1;
        visibility: visible;
        transform: translateY(0);
    }
    
    .navbar-nav {
        flex-direction: column;
        gap: 0;
        padding: var(--spacing-md);
    }
    
    .nav-item {
        width: 100%;
        border-bottom: 1px solid var(--border-light);
    }
    
    .nav-item:last-child {
        border-bottom: none;
    }
    
    .nav-link {
        padding: var(--spacing-md) 0;
        justify-content: space-between;
    }
    
    .dropdown-menu {
        position: static;
        box-shadow: none;
        border: none;
        background: var(--light-gray);
        margin-top: var(--spacing-sm);
        border-radius: var(--radius-sm);
    }
    
    .mobile-menu-toggle {
        display: flex;
    }
    
    .navbar-actions .btn {
        display: none;
    }
}

@media (max-width: 480px) {
    .announcement-item {
        flex-direction: column;
        gap: 4px;
        height: auto;
        padding: 4px 0;
    }
    
    .announcement-item span {
        text-align: center;
        line-height: 1.3;
    }
}