表头固定，表格内容滚动

适用于非多级表格 不足：表格内容未超出滚动高度，滚动条位置任然存在

<table>
    <thead>
        <tr>
            <th>1</th>
            <th>2</th>
            <th>3</th>
            <th>4</th>
            <th width="16"></th>
        </tr>
    </thead>
    <tbody>
        <tr>
            <td>11</td>
            <td>22</td>
            <td>33</td>
            <td>44</td>
        <tr>
    </tbody>
</table>

        table tbody {
            display: block;
            height: 490px;
            overflow-y: scroll;
        }
        table thead, tbody tr {
            display: table;
            width: 100%;
            table-layout: fixed;
        }