Question

Is it possible to create nested option fields in a form drop down, much like you would create nested ul lists?

Since the change is just aesthetical, is it possible to do this with css?

Answer 1

You can use <optgroup> to create a single level of nesting…

<select>
  <optgroup label="Options 1">
    <option>Option 1.1</option>
    <option>Option 1.2</option>
  </optgroup>
  <optgroup label="Options 2">
    <option>Option 2.1</option>
    <option>Option 2.2</option>
  </optgroup>
</select>

Note that the group labels are not selectable options. In that case, I would recommend using the text-indent solution that is mentioned in the top answer to the question that home linked to in his comment.