Cannot edit form style

Is it possible to edit the style of a form in Sites? I have tried editing the CSS of a custom theme, and the form style is the only part of the site that does not appear to be styled using the custom theme CSS.

I saw a solution that involved writing code for Creator, but to me that doesn't appeal. I want to control form look using CSS, not Creator scripts.

While Zoho Sites is a very nice tool, I'm starting to see the limitations that may have me looking for another solution.