I’m not too sure what the best way is to explain this so I’ll post images below. Quite obvious what’s wrong but not got a clue how to fix it! If you need code please let me know which bits exactly so I don’t spam you all
If you’re worried about the border-radius, this is a CSS3 property that isn’t supported on older browsers. There are lots of rounded corner techniques out there that don’t require CSS3, but they’re all pretty clunky (lots of containers, sometimes JavaScript). I’d either redesign the form or just ignore it.
Are you using an include to put the login form in there? You have a whole new page sitting inside the .login div (screenshot of source). Take all of that extra stuff out of the include and just have the <form> … </form> stuff inside the .login div.
raw10 is right – you’ve got one ENTIRE document pasted into another; that shouldn’t work ANYWHERE. You’ve got all sorts of other issues in there though ranging from DIV for NOTHING, none-semantic code, paragraphs around non-paragraph elements, dividers in the markup for no reason, code order that doesn’t exactly make sense, lack of headings, etc, etc…
You’d almost think it was in “transition” from 1997 to 1998. Oh wait…
“-//W3C//DTD XHTML 1.0 Transitional//EN”
… it is. That’s basically saying “I’m writing HTML 3.2 and then pretending I’m using modern techniques”.
If I were writing the same page, the code would probably be more like this: