/* 头部导航栏样式 */
.header {
    display: flex;
    gap: 30px;
    padding: 15px 40px;
    background: linear-gradient(135deg, #1a72ca, #28a7da);
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
    backdrop-filter: blur(5px); /* 毛玻璃效果 */
}

.headerItem {
    color: white;
    text-decoration: none;
    font-size: 1.2rem;
    font-weight: 500;
    position: relative;
    padding: 8px 0;
    transition: all 0.3s ease;
    display: inline-block;
}

/* 悬停下划线动画 */
.headerItem::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: #3498db;
    transition: width 0.3s;
}

.headerItem:hover {
    color: #3498db;
    transform: translateY(-2px);
}

.headerItem:hover::after {
    width: 100%;
}

/* 当前激活状态（需配合Jekyll的page.url判断） */
.headerItem.active {
    color: #3498db;
    font-weight: 600;
}

.headerItem.active::after {
    width: 100%;
    background: currentColor;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .header {
        flex-wrap: wrap;
        gap: 15px;
        justify-content: center;
        padding: 10px 20px;
    }

    .headerItem {
        font-size: 0.95rem;
        padding: 6px 0;
    }
}

/* 移动端优化 */
@media (max-width: 480px) {
    .header {
        flex-direction: column;
        align-items: center;
        gap: 10px;
    }
}