Add border around fieldsets

I thought it was a bug in my module because I was looking for a fieldset on a form and I could not find it. In fact, omega does not make fieldset very obvious, not as obvious as other themes do. To demonstrate, do a core search and open the advanced search fieldset, and note how it's hard to find the limit of the fieldset. Is that by design? I would advocate for having some form of wrapping border (even if it's a subtle color).