Well, since it's displaying properly in the preview page and not in your theme, that indicates it's a problem with your theme and not the default form styles. I poked around and found the source of your alignment issue.
If you disable the margin properties on lines 1755 & 2960 of your theme's style.css file, you'll see that the default form styles work as intended.
If you add extra margins/padding to the left & right sides of the containing list items, that' throws off the percentage width values that are assigned to them by default and you get the odd "stacking" floats that your seeing.
Posted 11 years ago on Monday July 11, 2011 | Permalink