We strive to let the forms inherit as many browser styles, and more specifically, theme styles as possible from the active theme, instead of trying to force styles on the site owner that may not fit what they’re going for. That said, we also can’t guarantee great results out of the box, depending on what styles may not be present already at those levels, and the site owner would need to touch up themselves. A bit of a less is more approach here.
If you provide a link, and what you would like to have it look like, I can try and give some basic style rules to pass along to the appropriate person.
