body {
    margin:0;
    font-family: "Microsoft YaHei", sans-serif;
    background:#f4f6f8;
}

/* 布局 */
.nav-container {
    display:flex;
}

/* 左侧 */
.nav-sidebar {
    width:220px;
    background:#2c3e50;
    color:#fff;
    height:100vh;
    padding:20px;
}

.nav-sidebar h2 {
    margin-bottom:20px;
}

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

.nav-sidebar li {
    margin:12px 0;
}

.nav-sidebar a {
    color:#ddd;
    text-decoration:none;
}

.nav-sidebar a:hover {
    color:#fff;
}

/* 内容区 */
.nav-content {
    flex:1;
    padding:30px;
}

header h1 {
    margin-bottom:20px;
}

/* 分类卡片 */
.category {
    background:#fff;
    padding:20px;
    border-radius:10px;
    margin-bottom:20px;
    box-shadow:0 5px 15px rgba(0,0,0,0.05);
}

.category h2 {
    border-bottom:2px solid #4a90e2;
    padding-bottom:8px;
    margin-bottom:15px;
}

/* 链接 */
.link-grid {
    display:grid;
    grid-template-columns: repeat(auto-fill, minmax(120px,1fr));
    gap:12px;
}

.link-grid a {
    display:block;
    padding:12px;
    text-align:center;
    background:#f1f3f5;
    border-radius:8px;
    text-decoration:none;
    color:#333;
    transition:0.2s;
}

.link-grid a:hover {
    background:#4a90e2;
    color:#fff;
    transform:translateY(-2px);
}