"Select Options" in Webform alignment

I am using a non-standard theme on my website, and I hope someone can suggest a simple solution (because I'm simple!) for a problem using the latest version of Webform.

In any standard theme a "Select Option" list displays correctly.

With my theme, provided by the original website designer, the radio buttons start next to the Label, instead of at the first option. Something like this:

Select day O
Monday O
Tuesday O
Wednesday

I didn't have this problem until the latest update of Webform and Arrange Fields.

Any suggestions, please?

More info - I have found that reverting to an old version of Arrange Fields has temporarily solved the problem in a dirty way. It has screwed up one of my webforms, though.