<div class="container">
  <table>
    <caption><small>Table width is set to 814px. The sum of widths of the columns is less than the table width, so the remaining space is distributed evenly over the columns.</small></caption>
    <tr>
      <td class="col-1">The width of this column is set to 200px.</td>
      <td class="col-2">The width of this column is set to 300px.</td>
    </tr>
    <tr>
      <td>content of third cell</td>
      <td>content four</td>
    </tr>
  </table>
</div>
<div class="container container-2">
  <table>
    <caption><small>Table width is set to 814px. The sum of widths of the columns is greater than the table width, so the table will expand to the sum of the widths.</small></caption>
    <tr>
      <td class="col-1">The width of this column is set to 600px.</td>
      <td class="col-2">The width of this column is set to 300px.</td>
    </tr>
    <tr>
      <td>content of third cell</td>
      <td>content four</td>
    </tr>
  </table>
</div>
@import url(http://fonts.googleapis.com/css?family=Lato:300,400,700,900);
body {
  background-color: #f5f5f5;
  color: #555;
  font-size: 1.1em;
  font-family: 'Lato', sans-serif;
}

.container {
  margin: 40px auto;
  width: 800px;
}

table,
td,
th {
  padding: 1em;
  border: 1px solid #ddd;
  text-align: left;
}

table {
  table-layout: fixed;
  width: 814px;
  background-color: white;
}

caption {
  caption-side: bottom;
  font-style: italic;
}

.col-1 {
  width: 200px;
}

.col-2 {
  width: 300px;
}

.container-2 .col-1 {
  width: 600px;
}

.container-2 .col-2 {
  width: 300px;
}