Need HELP PLEASE!!! Unable to get into "Customize Site" mode

Theon

PLEASE HELP. I added a Site wide banner and im guessing i put something wrong maybe in the CSS because now when i click on the customize site link, the page loads but then goes blank and the only thing left is the menu and footer but none of the links work. NEED HELP:scratch Site is http://theonrichards.smugmug.com/