By all means allow users to customise the css as they like it but you shouldn't need to do this to "fix the problem", the default should already be fixed, it's not laziness... just saying :)

The huge expanses of space between elements is just daft.

Why three lines between paragraphs?

I shouldn't have to scroll to get to the Post Reply button for this comment box...

The "joined date" for my profile on the left here is split over two lines because of the css - it doesn't need to be, the date for Khai-J-Bach above is fine because the width needed is less. Sloppy.