/* 全局样式 */
body {
    font-family: \'Segoe UI\', Tahoma, Geneva, Verdana, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #0a192f; /* 深蓝色背景 */
    color: #e2e8f0;
    line-height: 1.6;
}

#app {
    display: flex;
    min-height: 100vh;
}

/* 左侧固定导航栏 */
.sidebar {
    width: 220px;
    background-color: #001f3f; /* 更深的蓝色 */
    color: #ffffff;
    padding: 20px;
    box-shadow: 2px 0 5px rgba(0, 0, 0, 0.2);
    position: fixed;
    height: 100%;
    overflow-y: auto;
}

.sidebar nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.sidebar nav ul li {
    margin-bottom: 15px;
}

.sidebar nav ul li a {
    color: #ffffff;
    text-decoration: none;
    font-size: 1.1em;
    padding: 10px 15px;
    display: block;
    border-radius: 8px; /* 圆角 */
    transition: background-color 0.3s ease, color 0.3s ease;
}

.sidebar nav ul li a:hover,
.sidebar nav ul li a.active {
    background-color: #007bff; /* 蓝色高亮 */
    color: #ffffff;
}

/* 主内容区域 */
.main-content {
    margin-left: 220px; /* 留出导航栏的空间 */
    flex-grow: 1;
    padding: 30px;
}

header {
    background-color: #001f3f; /* 与导航栏颜色一致 */
    padding: 20px 30px;
    margin-bottom: 30px;
    border-radius: 12px; /* 圆角 */
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
}

header h1 {
    color: #007bff;
    font-size: 2.5em;
    margin: 0;
    text-align: center;
}

/* 卡片式布局 */
.card-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
}

.card {
    background-color: #002a5c; /* 较浅的深蓝色 */
    padding: 25px;
    border-radius: 12px; /* 圆角卡片 */
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.4);
}

.card h2 {
    color: #007bff;
    font-size: 1.8em;
    margin-top: 0;
    margin-bottom: 15px;
    border-bottom: 2px solid #004080; /* 底部边框 */
    padding-bottom: 10px;
}

.card p {
    color: #c0ccda;
    font-size: 1em;
    margin-bottom: 10px;
}

/* 响应式设计 */
@media (max-width: 768px) {
    #app {
        flex-direction: column;
    }

    .sidebar {
        width: 100%;
        position: relative;
        height: auto;
        box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
    }

    .main-content {
        margin-left: 0;
        padding: 20px;
    }

    .sidebar nav ul {
        display: flex;
        flex-wrap: wrap;
        justify-content: center;
    }

    .sidebar nav ul li {
        margin: 5px 10px;
    }

    .sidebar nav ul li a {
        padding: 8px 12px;
        font-size: 1em;
    }

    header {
        padding: 15px 20px;
        margin-bottom: 20px;
    }

    header h1 {
        font-size: 2em;
    }

    .card-section {
        grid-template-columns: 1fr;
        gap: 20px;
    }

    .card {
        padding: 20px;
    }

    .card h2 {
        font-size: 1.5em;
    }
}