Changing the menu bar and header appearance

Hi! I had two questions: My site has some sections (categories, Home and About) in the navigation bar, but there's still an empty space at the far right! Can I remove the borders of the navigation bar so that empty space isn't so obvious? (Also open to other ways to change its appearance to make it look a little bit more polished.) Also: Is there any way to remove the grainy grey background in the header? I'd like my header image to sit against a white background if possible, because the image itself has a white background. My site is: http://www.theprocrastiwriter.com/ Thanks! S