@import url('tokens.css');
@import url('components.css');

/* ==================== 导航栏 (Navbar) ==================== */
nav {
    background-color: var(--color-bg-white);
    border-bottom: 1px solid var(--color-border-light);
    padding: 14px 0;
    position: sticky;
    top: 0;
    z-index: var(--z-sticky);
    box-shadow: var(--shadow-sm);
}

.nav {
    box-sizing: border-box;
    display: flex;
    justify-content: flex-start;
    align-items: center;
    gap: 36px;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.nav a {
    text-decoration: none;
    color: var(--color-text-secondary);
    font-size: var(--font-size-md);
    font-weight: 600;
    transition: color var(--transition-fast);
    position: relative;
    padding: 4px 0;
}

.nav a:hover {
    color: var(--color-primary);
}

.nav a.active {
    font-weight: 700;
    color: var(--color-primary);
}

.nav a.active::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -18px;
    width: 100%;
    height: 3px;
    background-color: var(--color-primary);
    border-radius: 2px 2px 0 0;
}

/* ==================== 导航下拉菜单 (Nav Dropdown) ==================== */
.nav-dropdown {
    position: relative;
    display: inline-flex;
}

.nav-dropdown::after {
    content: '';
    position: absolute;
    top: 100%;
    left: 0;
    width: 100%;
    height: 16px;
}

.dropdown-trigger {
    color: var(--color-text-secondary);
    font-size: var(--font-size-md);
    font-weight: 600;
    cursor: pointer;
    transition: color var(--transition-fast);
    position: relative;
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 4px 0;
}

.dropdown-trigger:hover {
    color: var(--color-primary);
}

.dropdown-trigger.active {
    font-weight: 700;
    color: var(--color-primary);
}

.dropdown-trigger.active::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: -18px;
    width: 100%;
    height: 3px;
    background-color: var(--color-primary);
    border-radius: 2px 2px 0 0;
}

.dropdown-trigger .fa-chevron-down {
    font-size: 10px;
    transition: transform var(--transition-fast);
}

.nav-dropdown:hover .dropdown-trigger .fa-chevron-down {
    transform: rotate(180deg);
}

.dropdown-menu {
    display: none;
    position: absolute;
    top: 100%;
    left: 50%;
    transform: translateX(-50%);
    margin-top: 16px;
    background: var(--color-bg-white);
    border: 1px solid var(--color-border);
    border-radius: var(--border-radius);
    box-shadow: var(--shadow-lg);
    min-width: 220px;
    z-index: var(--z-dropdown);
    padding: 8px 0;
}

.nav-dropdown:hover .dropdown-menu {
    display: block;
}

.dropdown-menu a {
    display: block;
    padding: 10px 20px;
    color: var(--color-text-secondary);
    font-size: var(--font-size-sm);
    font-weight: 500;
    text-decoration: none;
    white-space: nowrap;
    transition: background var(--transition-fast), color var(--transition-fast);
}

.dropdown-menu a:hover {
    background: var(--color-primary-light);
    color: var(--color-primary);
}

.dropdown-menu a:first-child {
    border-radius: var(--border-radius) var(--border-radius) 0 0;
}

.dropdown-menu a:last-child {
    border-radius: 0 0 var(--border-radius) var(--border-radius);
}

/* ==================== 移动端导航 (Mobile Navigation) ==================== */
.nav-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--color-text-secondary);
    font-size: 22px;
    cursor: pointer;
    padding: 4px 8px;
}

@media (max-width: 900px) {
    .nav-toggle {
        display: block;
    }

    .nav {
        flex-wrap: wrap;
        gap: 0;
    }

    .nav-link-list {
        display: none;
        flex-direction: column;
        width: 100%;
        padding: 12px 0 4px 0;
        gap: 6px;
    }

    .nav-link-list.open {
        display: flex;
    }

    .nav-link-list .nav-dropdown {
        flex-direction: column;
    }

    .nav-link-list .dropdown-menu {
        position: static;
        transform: none;
        margin-top: 6px;
        box-shadow: none;
        border: 1px solid var(--color-border-light);
        border-radius: var(--border-radius);
        background: var(--color-bg-gray);
    }

    .nav-link-list .dropdown-menu a {
        padding: 8px 28px;
    }

    .nav a {
        padding: 8px 0;
    }

    .nav a.active::after,
    .dropdown-trigger.active::after {
        bottom: 0;
    }
}

/* ==================== 全局 Footer ==================== */
.site-footer {
    background-color: #f8f9fa;
    border-top: 1px solid var(--color-border-light);
    padding: 28px 0;
    margin-top: 40px;
    color: #666;
    font-size: 14px;
}

.footer-content {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    gap: 20px;
}

.footer-info p {
    margin: 4px 0;
}

.footer-links {
    display: flex;
    gap: 24px;
}

.footer-links a {
    color: #666;
    text-decoration: none;
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--color-primary);
}

.footer-citation {
    color: #777;
    font-size: 13px;
}

@media (max-width: 768px) {
    .footer-content {
        flex-direction: column;
        text-align: center;
    }
}