Radio/checkbox alignment in HTML/CSS

Question

What is the cleanest way to align properly radio buttons / checkboxes with text? The only reliable solution which I have been using so far is table based:

<table>
<tr>
    <td><input type="radio" name="opt"></td>
    <td>Option 1</td>
</tr>
<tr>
    <td><input type="radio" name="opt"></td>
    <td>Option 2</td>
</tr>
</table>

This may be frown upon by some. I’ve just spent some time (again) investigating a tableless solution but failed. I’ve tried various combinations of floats, absolute/relative positioning and similar approaches. Not only that they mostly relied silently on an estimated height of the radio buttons / checkboxes, but they also behaved differently in different browsers. Ideally, I would like to find a solution which does not assume anything about sizes or special browser quirks. I’m fine with using tables, but I wonder where there is another solution.

Answer 1

I think I have finally solved the problem. One commonly recommended solution is to use vertical-align: middle:

<input type="radio" style="vertical-align: middle"> Label

The problem, however, is that this still produces visible misalignments even though it should theoretically work. The CSS2 specification says that:

vertical-align: middle: Align the vertical midpoint of the box with the baseline of the parent box plus half the x-height of the parent.

So it should be in the perfect centre (the x-height is the height of the character x). However, the problem seems to be caused by the fact browsers commonly add some random uneven margins to radio buttons and checkboxes. One can check, for instance in Firefox using Firebug, that the default checkbox margin in Firefox is 3px 3px 0px 5px. I'm not sure where it comes from, but the other browsers seem to have similar margins as well. So to get a perfect alignment, one needs to get rid of these margins:

<input type="radio" style="vertical-align: middle; margin: 0px;"> Label

It is still interesting to note that in the table based solution the margins are somehow eaten and everything aligns nicely.