/* ============================================
 * 模块: 头部导航
 * 文件: assets/css/header.css
 * 依赖: main.css
 * @since 3.0.0
 * ============================================ */

/* ---------- 顶部公告栏 ---------- */
.topbar {
    background: var(--color-primary);
    color: #fff;
    font-size: var(--font-size-sm);
    line-height: var(--line-height-tight);
    overflow: hidden;
    transition: max-height 0.3s ease, opacity 0.3s ease;
}
.topbar .container {
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 36px;
    padding-top: var(--spacing-xs);
    padding-bottom: var(--spacing-xs);
    gap: var(--spacing-md);
}
.topbar__content {
    flex: 1;
    text-align: center;
}
.topbar__content a {
    color: #fff;
    text-decoration: underline;
}
.topbar__close {
    flex-shrink: 0;
    background: none;
    border: none;
    color: #fff;
    cursor: pointer;
    padding: var(--spacing-xs);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-circle);
    transition: background var(--transition-base);
}
.topbar__close:hover {
    background: rgba(255, 255, 255, 0.15);
}

/* ---------- 站点头部 ---------- */
.site-header {
    position: sticky;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    height: var(--header-height);
    background: var(--color-bg-container);
    transition: box-shadow var(--transition-base);
}
.site-header--scrolled {
    box-shadow: var(--shadow-1);
}
.site-header .container {
    display: flex;
    align-items: center;
    height: 100%;
    gap: var(--spacing-xxl);
}

/* Logo */
.site-header__logo {
    flex-shrink: 0;
    display: flex;
    align-items: center;
}
.site-header__logo .custom-logo-link img {
    max-height: 40px;
    width: auto;
}
.site-header__logo-text {
    font-size: var(--font-size-lg);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    text-decoration: none;
    white-space: nowrap;
}

/* ---------- 主导航菜单 ---------- */
.site-header__nav {
    flex: 1;
    display: flex;
    justify-content: center;
}

.nav-menu {
    display: flex;
    align-items: center;
    list-style: none;
    gap: var(--spacing-xs);
}
.nav-menu li {
    position: relative;
}
.nav-menu a {
    display: block;
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    text-decoration: none;
    border-radius: var(--radius-small);
    transition: color var(--transition-base), background var(--transition-base);
    white-space: nowrap;
}
.nav-menu a:hover,
.nav-menu .current-menu-item > a,
.nav-menu .current-menu-ancestor > a {
    color: var(--color-primary);
    background: var(--color-primary-lighter);
}

/* 下拉子菜单 */
.nav-menu .sub-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    min-width: 180px;
    padding: var(--spacing-xs) 0;
    background: var(--color-bg-container);
    border-radius: var(--radius-medium);
    box-shadow: var(--shadow-2);
    list-style: none;
    z-index: 100;
}
.nav-menu .menu-item-has-children:hover > .sub-menu {
    display: block;
}
.nav-menu .sub-menu a {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-sm);
    border-radius: 0;
}
.nav-menu .sub-menu a:hover {
    background: var(--color-bg-hover);
}

/* ---------- 右侧操作区 ---------- */
.site-header__actions {
    flex-shrink: 0;
    display: flex;
    align-items: center;
    gap: var(--spacing-md);
}
.site-header__cta {
    white-space: nowrap;
}

/* 汉堡菜单按钮（PC 端默认隐藏） */
.site-header__menu-toggle {
    display: none;
    background: none;
    border: none;
    cursor: pointer;
    padding: var(--spacing-xs);
    color: var(--color-text-primary);
}
.site-header__menu-toggle:hover {
    color: var(--color-primary);
}


/* ---------- 占位高度 ---------- */
.header-placeholder {
    height: var(--header-height);
}

/* ---------- 移动端侧边栏导航（PC 响应式回退） ---------- */
.mobile-nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 9999;
    pointer-events: none;
    visibility: hidden;
    opacity: 0;
    transition: visibility 0s 0.3s, opacity 0.3s ease;
}
.mobile-nav--open {
    pointer-events: auto;
    visibility: visible;
    opacity: 1;
    transition: visibility 0s 0s, opacity 0.3s ease;
}
.mobile-nav__overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    opacity: 0;
    transition: opacity 0.3s ease;
}
.mobile-nav--open .mobile-nav__overlay {
    opacity: 1;
}
.mobile-nav__panel {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    width: 280px;
    max-width: 80vw;
    background: var(--color-bg-container);
    transform: translateX(100%);
    transition: transform 0.3s ease;
    display: flex;
    flex-direction: column;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
}
.mobile-nav--open .mobile-nav__panel {
    transform: translateX(0);
}
.mobile-nav__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border-light);
    height: 56px;
    flex-shrink: 0;
}
.mobile-nav__title {
    font-size: var(--font-size-md);
    font-weight: var(--font-weight-medium);
    color: var(--color-text-primary);
}
.mobile-nav__close {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    background: transparent;
    border: none;
    border-radius: var(--radius-medium);
    color: var(--color-text-primary);
    cursor: pointer;
    padding: 0;
    transition: background var(--transition-base);
}
.mobile-nav__close:hover {
    background: var(--color-bg-hover);
}
.mobile-nav__menu {
    list-style: none;
    padding: var(--spacing-sm) 0;
    margin: 0;
    flex: 1;
    overflow-y: auto;
}
.mobile-nav__menu li {
    margin: 0;
}
.mobile-nav__menu a {
    display: block;
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
    color: var(--color-text-primary);
    text-decoration: none;
    transition: background var(--transition-base), color var(--transition-base);
    border-left: 3px solid transparent;
}
.mobile-nav__menu a:hover,
.mobile-nav__menu a:active {
    background: var(--color-bg-hover);
    color: var(--color-primary);
}
.mobile-nav__menu .current-menu-item > a {
    color: var(--color-primary);
    background: var(--color-primary-lighter);
    border-left-color: var(--color-primary);
}
/* 二级菜单 */
.mobile-nav__menu .sub-menu {
    list-style: none;
    padding: 0;
    margin: 0;
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.3s ease;
}
.menu-item--expanded > .sub-menu {
    max-height: 500px;
}
.mobile-nav__menu .sub-menu a {
    padding-left: var(--spacing-xxl);
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
}
/* 展开箭头 */
.mobile-nav__menu .menu-item-has-children > a {
    position: relative;
    padding-right: var(--spacing-xxxl);
}
.mobile-nav__menu .menu-item-has-children > a::after {
    content: '';
    position: absolute;
    right: var(--spacing-xl);
    top: 50%;
    width: 8px;
    height: 8px;
    border-right: 1.5px solid var(--color-text-placeholder);
    border-bottom: 1.5px solid var(--color-text-placeholder);
    transform: translateY(-70%) rotate(45deg);
    transition: transform 0.3s ease;
}
.menu-item--expanded > a::after {
    transform: translateY(-30%) rotate(-135deg);
}
.mobile-nav__cta {
    margin: var(--spacing-lg) var(--spacing-xl);
    flex-shrink: 0;
    width: auto;
}

/* ---------- 响应式：平板以下显示汉堡菜单 ---------- */
@media (max-width: 992px) {
    .site-header__nav {
        display: none;
    }
    .site-header__menu-toggle {
        display: flex;
        align-items: center;
        justify-content: center;
    }
    .site-header .container {
        gap: var(--spacing-md);
    }
    /* 响应式下隐藏 PC CTA，改用侧边栏中的 CTA */
    .site-header__cta {
        display: none;
    }
}