revision:
The span attribute defines the number of columns a <col> or <colgroup> element should span.
The span attribute can be used on the following elements: <col> and <colgroup>
<element span="number"></element>
number: an integer greater than zero indicating a number of columns of a table. Default value of HTML span attribute is 1.
| ISBN | Title | Price |
|---|---|---|
| 3476896 | My first HTML | $53 |
| 5869207 | My first CSS | $49 |
<table style="margin-left:3vw;">
<colgroup>
<col span="2" style="background-color:red">
<col style="background-color:yellow">
</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>
<style>
table, th, td {border: 1px solid black;}
</style>
| ISBN | Title | Price |
|---|---|---|
| 3476896 | My first HTML | $53 |
| 5869207 | My first CSS | $49 |
<table style="margin-left:3vw;">
<colgroup span="2" style="background:red"></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>
<style>
table, th, td {border: 1px solid black;}
</style>