Can I color table columns using CSS without coloring individual cells?

Answer 1

Yes, you can... using the <col> element:

.grey {
  background-color: rgba(128,128,128,.25);
}
.red {
  background-color: rgba(255,0,0,.25);
}
.blue {
  background-color: rgba(0,0,255,.25);
}

<table>
  <colgroup>
    <col class="grey" />
    <col class="red" span="3" />
    <col class="blue" />
  </colgroup>
  <thead>
    <tr>
      <th>#</th>
      <th colspan="3">color 1</th>
      <th>color 2</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <th>1</th>
      <td>red</td>
      <td>red</td>
      <td>red</td>
      <td>blue</td>
    </tr>
    <tr>
      <th>2</th>
      <td>red</td>
      <td>red</td>
      <td>red</td>      
      <td>blue</td>
    </tr>
  </tbody>
</table>

_{Note: You can use the span attribute to make the col definition apply to more than one column.
See also: <colgroup>}

Answer 2

You can use the nth-child selector for that:

tr td:nth-child(2),
tr td:nth-child(3) {
  background: #ccc;
}

<table>
  <tr>
    <th colspan="2">headline 1</th>
    <th>headline 2</th>
  </tr>
  <tr>
    <td>column 1</td>
    <td>column 2</td>
    <td>column 3</td>
  </tr>
  <tr>
    <td>column 1</td>
    <td>column 2</td>
    <td>column 3</td>
  </tr>
  <tr>
    <td>column 1</td>
    <td>column 2</td>
    <td>column 3</td>
  </tr>
</table>

Answer 3

You can use CSS3: http://jsfiddle.net/snuggles08/bm98g8v8/

<style>
  .table td:nth-of-type(1) {
    background: red;
  }
  .table td:nth-of-type(5) {
    background: blue;
  }
  .table td:nth-of-type(3) {
    background: green;
  }
  .table td:nth-of-type(7) {
    background: lime;
  }
  .table td:nth-of-type(2) {
    background: skyblue;
  }
  .table td:nth-of-type(4) {
    background: darkred;
  }
  .table td:nth-of-type(6) {
    background: navy;
  }
</style>
Styled table:
<table border="1" class="table">
  <tbody>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
      <td>4</td>
      <td>5</td>
      <td>6</td>
      <td>7</td>
    </tr>
    <tr>
      <td>7</td>
      <td>1</td>
      <td>2</td>
      <td>3</td>
      <td>4</td>
      <td>5</td>
      <td>6</td>
    </tr>
  </tbody>
</table>
<hr>Unstyled table:
<table border="1" class="table2">
  <tbody>
    <tr>
      <td>1</td>
      <td>2</td>
      <td>3</td>
      <td>4</td>
      <td>5</td>
      <td>6</td>
      <td>7</td>
    </tr>
    <tr>
      <td>7</td>
      <td>1</td>
      <td>2</td>
      <td>3</td>
      <td>4</td>
      <td>5</td>
      <td>6</td>
    </tr>
  </tbody>
</table>

Answer 4

It is generally simplest to style cells (by column if desired), but columns can be styled, in different ways. One simple way is to wrap columns in a colgroup element and set styles on it. Example:

<style>
.x {
    background-color: #DDD
}
</style>
<table border="1">
<col>
<colgroup class=x>
  <col>
  <col>
  <col>
</colgroup>
<col>
<colgroup class=x>
  <col>
  <col>
</colgroup>
  <tr>
    <th>Motor</th>
    <th colspan="3" class="color">Engine</th>
    <th>Car</th>
    <th colspan="2" class="color">Body</th>
  </tr>
  <tr>
    <td>1</td>
    <td class="color">2</td>
    <td class="color">3</td>
    <td class="color">4</td>
    <td>5</td>
    <td class="color">6</td>
    <td class="color">7</td>
  </tr>
  <tr>
    <td>7</td>
    <td class="color">1</td>
    <td class="color">2</td>
    <td class="color">3</td>
    <td>4</td>
    <td class="color">5</td>
    <td class="color">6</td>
  </tr>
</table>

Answer 5

My version using nth-child expressions:

Using the CSS concept of cascade rules to first coloring the cells and then to uncolor the ones i want to be transparent. The first selector selects all the cells after the first one, and the second one selects the fifth cell to be transparent.

<style type="text/css">
  /* colored */
  td:nth-child(n+2) { background-color: #ffffd }
  /* uncolored */
  td:nth-child(5) { background-color: transparent }
</style>

<table border="1">
  <tr>
    <th>Motor</th>
    <th colspan="3">Engine</th>
    <th>Car</th>
    <th colspan="2">Body</th>
  </tr>
  <tr>
    <td>1</td>
    <td>2</td>
    <td>3</td>
    <td>4</td>
    <td>5</td>
    <td>6</td>
    <td>7</td>
  </tr>
  <tr>
    <td>7</td>
    <td>1</td>
    <td>2</td>
    <td>3</td>
    <td>4</td>
    <td>5</td>
    <td>6</td>
  </tr>
</table>

Check this interesting reference: http://learn.shayhowe.com/advanced-html-css/complex-selectors/

Answer 6

The following implement's the nth-child selector and should work...

<style type="text/css">
    th:nth-child(2),
    th:nth-child(4)
    {
        background-color: rgba(255, 0, 0, 1.0);
    }

    td:nth-child(2), 
    td:nth-child(3),
    td:nth-child(4),
    td:nth-child(6),
    td:nth-child(7)
    {
        background-color: rgba(255, 0, 0, 0.5);
    }
</style>