表头固定内容滚动的表格

HTML

<div class="m-demo">
    <table>
        <thead>
           <tr><th>定宽a</th><th>定宽b</th><th>定宽c</th><th>最后列不定宽d</th></tr>
        </thead>
    </table>
    <div class="scroll">
        <table>
            <tbody>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
            </tbody>
        </table>
    </div>
</div>
<div class="m-demo">
	<table>
        <thead>
           <tr><th>定宽a</th><th>定宽b</th><th>定宽c</th><th>最后列不定宽d</th></tr>
        </thead>
    </table>
	<div class="scroll">
	    <table>
            <tbody>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
                <tr><td>定宽a</td><td>定宽b</td><td>定宽c</td><td>最后列不定宽d</td></tr>
            </tbody>
        </table>
    </div>
</div>
					    

CSS

/* 预览辅助样式 */
body{margin:20px;}
html,body,h1,h2,h3,h4,h5,h6,div,dl,dt,dd,ul,ol,li,p,blockquote,pre,hr,figure,table,caption,th,td,form,fieldset,legend,input,button,textarea,menu{margin:0;padding:0;}
header,footer,section,article,aside,nav,hgroup,address,figure,figcaption,menu,details{display:block;}
table{border-collapse:collapse;border-spacing:0;}
/* 表头固定内容滚动的表格  */
.m-demo{margin:0 0 20px;line-height:18px;}
.m-demo .scroll{max-height:116px;border:1px solid #ddd;border-top:0;overflow-y:auto;}
.m-demo table{width:100%;table-layout:fixed;}
.m-demo th,.m-demo td{width:100px;padding:10px;border:1px solid #ddd;}
.m-demo th{font-weight:bold;background:#eee;}
.m-demo thead th:last-child,.m-demo tbody td:last-child{width:auto;}
.m-demo tbody tr:nth-child(2n){background:#fafafa;}
.m-demo tbody tr:first-child td{border-top:0;}
.m-demo tbody tr:last-child td{border-bottom:0;}
.m-demo tbody tr td:first-child{border-left:0;}
.m-demo tbody tr td:last-child{border-right:0;}