You could try using the <col> tag manage table styling for all rows but you will need to set the table-layout:fixed style on the <table> or the tables css class and set the overflow style for the cells

http://www.w3schools.com/TAGS/tag_col.asp

<table class="fixed">
    <col width="20px" />
    <col width="30px" />
    <col width="40px" />
    <tr>
        <td>text</td>
        <td>text</td>
        <td>text</td>
    </tr>
</table>

and this be your CSS

table.fixed { table-layout:fixed; }
table.fixed td { overflow: hidden; }

I played with it for a bit because I had trouble figuring it out.

You need to set the cell width (either th or td worked, I set both) AND set the table-layout to fixed. For some reason, the cell width seems to only stay fixed if the table width is set, too (I think that's silly but whatev).

Also, it is useful to set the overflow property to hidden to prevent any extra text from coming out of the table.

You should make sure to leave all of the bordering and sizing for CSS, too.

Ok so here's what I have:

table {
  border: 1px solid black;
  table-layout: fixed;
  width: 200px;
}

th,
td {
  border: 1px solid black;
  width: 100px;
  overflow: hidden;
}

<table>
  <tr>
    <th>header 1</th>
    <th>header 234567895678657</th>
  </tr>
  <tr>
    <td>data asdfasdfasdfasdfasdf</td>
    <td>data 2</td>
  </tr>
</table>

Here it is in JSFiddle

This guy had a similar problem: Table cell widths - fixing width, wrapping/truncating long words