/* 头部样式 */
.header {
    background: #fff;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 80px;
}

.logo {
    flex: 0 0 200px;
}

.logo h1 {
    font-size: 24px;
    color: #333;
    font-weight: bold;
}

/* 导航样式 */
.nav ul {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav a {
    text-decoration: none;
    color: #333;
    font-size: 16px;
    padding: 10px 0;
    position: relative;
    transition: color 0.3s ease;
}

.nav a:hover {
    color: #f00;
}

.nav a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background: #f00;
    transition: width 0.3s ease;
}

.nav a:hover::after {
    width: 100%;
}

/* 响应式导航 */
@media screen and (max-width: 768px) {
    .header .container {
        flex-direction: column;
        height: auto;
        padding: 15px;
    }

    .logo {
        margin-bottom: 15px;
    }

    .nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 15px;
    }

    .nav a {
        padding: 5px 10px;
    }
}