Thank you for the answers!
Toxaris, that is exactly what I've done here before. The problem is, that the spacing is not always equal, especially when numbers have more than one position.
Jellby, yep, that was my intention. Your answer is not quite what I hoped for, but it seems there is no other way than using tables. (I don't like floats, they always mess up things
) Maybe W3C should work on this issue for their next CSS/HTML standards…