<style>
table, th, td {
    border: 1px solid black;
/* width:500px; 寬度也可以加在這裡*/
}
</style>

<div>
<table>
  <colgroup>
    <col span="1" style="background-color:red">
    <col style="background-color:yellow; /*去除註解符號就可以加上寬度 width:500px;*/">
  </colgroup>
  <tr>
    <th>ISBN</th>
    <th>Title</th>
    <th>Price</th>
  </tr>
  <tr>
    <td>3476896</td>
    <td>My first HTML</td>
    <td>$53</td>
  </tr>
  <tr>
    <td>5869207</td>
    <td>My first CSS</td>
    <td>$49</td>
  </tr>
</table>
</div>