/* 基础样式 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Microsoft YaHei', sans-serif;
    background: #f5f5f5;
}

/* 头部样式 */
.main-header {
    background: #fff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 100;
}

.logo {
    color: #e67e22;
    text-align: center;
    padding: 15px 0;
    font-size: 2.2em;
}

/* 导航栏 */
.main-nav {
    border-top: 2px solid #eee;
}

.nav-list {
    display: flex;
    justify-content: center;
    list-style: none;
}

.nav-item {
    color: #666;
    text-decoration: none;
    padding: 15px 25px;
    transition: all 0.3s;
    position: relative;
}

.nav-item.active {
    color: #e67e22;
    font-weight: bold;
}

.nav-item.active::after {
    content: '';
    position: absolute;
    bottom: -2px;
    left: 50%;
    transform: translateX(-50%);
    width: 60%;
    height: 3px;
    background: #e67e22;
}

.nav-item:hover {
    color: #d35400;
}

/* 内容容器 */
.content-container {
    margin-top: 120px;
    padding: 20px 5%;
}

.content-frame {
    width: 100%;
    height: calc(100vh - 160px);
    display: none;
    border-radius: 10px;
    background: #fff;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
}

.content-frame.active {
    display: block;
    animation: fadeIn 0.3s;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.welcome-section {
    text-align: center;
    padding: 60px 20px;
    max-width: 1200px;
    margin: 0 auto;
}

.welcome-section h1 {
    font-size: 36px;
    color: #333;
    margin-bottom: 20px;
    animation: fadeInUp 0.8s ease;
}

.welcome-section p {
    font-size: 18px;
    color: #666;
    margin-bottom: 50px;
    animation: fadeInUp 1s ease;
}

.feature-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    padding: 20px;
    animation: fadeInUp 1.2s ease;
}

.feature-card {
    background: white;
    border-radius: 15px;
    padding: 30px;
    text-align: center;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
}

.feature-card i {
    font-size: 48px;
    color: var(--primary-color);
    margin-bottom: 20px;
}

.feature-card h3 {
    font-size: 24px;
    color: #333;
    margin-bottom: 15px;
}

.feature-card p {
    font-size: 16px;
    color: #666;
    line-height: 1.6;
}

@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式调整 */
@media (max-width: 768px) {
    .welcome-section h1 {
        font-size: 28px;
    }

    .welcome-section p {
        font-size: 16px;
    }

    .feature-cards {
        grid-template-columns: 1fr;
        gap: 20px;
    }
}