body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: #f5f5f5;
}

/* 左侧菜单 */
.sidebar {
    width: 220px;
    height: 100vh;
    background: #111;
    color: #fff;
    position: fixed;
    left: 0;
    top: 0;
}

.sidebar h2 {
    text-align: center;
    padding: 20px 0;
    border-bottom: 1px solid #333;
}

.sidebar a {
    display: block;
    padding: 12px 20px;
    color: #ccc;
    text-decoration: none;
}

.sidebar a:hover {
    background: #222;
    color: #fff;
}

/* 主内容 */
.main {
    margin-left: 220px;
    padding: 20px;
}

/* 卡片 */
.card {
    background: #fff;
    padding: 20px;
    border-radius: 8px;
    margin-bottom: 20px;
}

/* 表格 */
table {
    width: 100%;
    border-collapse: collapse;
}

th {
    background: #eee;
    padding: 10px;
    text-align: left;
}

td {
    padding: 10px;
    border-bottom: 1px solid #ddd;
}

/* 按钮 */
button {
    background: #111;
    color: #fff;
    border: none;
    padding: 8px 14px;
    border-radius: 6px;
    cursor: pointer;
}

button:hover {
    background: #333;
}

/* 输入框 */
input, select {
    padding: 8px;
    width: 100%;
    margin-bottom: 10px;
    border: 1px solid #ccc;
    border-radius: 6px;
}

/* 表单 */
.form-group {
    margin-bottom: 15px;
}