Table with fixed thead inside of position:absolute block - html

Question

I have a HTML table wrapped by a block with position:absolute. I want to make the first row (with a th or td, or wrapped by thead) fixed at the top, and other table should be scrollable, without fixed height.
I've tried this, but inside of position:absolute it didn't work:
https://jsfiddle.net/dPixie/byB9d/3/light/
html, body{
margin:0;
padding:0;
height:100%;
}
section {
position: relative;
border: 1px solid #000;
padding-top: 37px;
background: #500;
}
section.positioned {
position: absolute;
top:100px;
left:100px;
width:800px;
box-shadow: 0 0 15px #333;
}
.container {
overflow-y: auto;
height: 200px;
}
table {
border-spacing: 0;
width:100%;
}
td + td {
border-left:1px solid #eee;
}
td, th {
border-bottom:1px solid #eee;
background: #ddd;
color: #000;
padding: 10px 25px;
}
th {
height: 0;
line-height: 0;
padding-top: 0;
padding-bottom: 0;
color: transparent;
border: none;
white-space: nowrap;
}
th div{
position: absolute;
background: transparent;
color: #fff;
padding: 9px 25px;
top: 0;
margin-left: -25px;
line-height: normal;
border-left: 1px solid #800;
}
th:first-child div{
border: none;
}
<section class="">
<div class="container">
<table>
<thead>
<tr class="header">
<th>
Table attribute name
<div>Table attribute name</div>
</th>
<th>
Value
<div>Value</div>
</th>
<th>
Description
<div>Description</div>
</th>
</tr>
</thead>
<tbody>
<tr>
<td>align</td>
<td>left, center, right</td>
<td>Not supported in HTML5. Deprecated in HTML 4.01. Specifies the alignment of a table according to surrounding text</td>
</tr>
<tr>
<td>bgcolor</td>
<td>rgb(x,x,x), #xxxxxx, colorname</td>
<td>Not supported in HTML5. Deprecated in HTML 4.01. Specifies the background color for a table</td>
</tr>
<tr>
<td>border</td>
<td>1,""</td>
<td>Specifies whether the table cells should have borders or not</td>
</tr>
<tr>
<td>cellpadding</td>
<td>pixels</td>
<td>Not supported in HTML5. Specifies the space between the cell wall and the cell content</td>
</tr>
<tr>
<td>cellspacing</td>
<td>pixels</td>
<td>Not supported in HTML5. Specifies the space between cells</td>
</tr>
<tr>
<td>frame</td>
<td>void, above, below, hsides, lhs, rhs, vsides, box, border</td>
<td>Not supported in HTML5. Specifies which parts of the outside borders that should be visible</td>
</tr>
<tr>
<td>rules</td>
<td>none, groups, rows, cols, all</td>
<td>Not supported in HTML5. Specifies which parts of the inside borders that should be visible</td>
</tr>
<tr>
<td>summary</td>
<td>text</td>
<td>Not supported in HTML5. Specifies a summary of the content of a table</td>
</tr>
<tr>
<td>width</td>
<td>pixels, %</td>
<td>Not supported in HTML5. Specifies the width of a table</td>
</tr>
</tbody>
</table>
</div>
</section>