Okay, [here it is.](http://codepen.io/wolfcry911/pen/LlBHF “”)
I see you’ve used box-sizing: border-box; which isn’t bad, but I feel you should learn the box model in and out before using this (it has no effect on anything you’ve done thus far), so I’ve eliminated it.
I cleaned up the #header area. I eliminated a lot of unnecessary divs, and to be honest I could eliminate #mast and #below-mast, but kept them there for the time being.
Classing a div as a header in place of using a header is bad both semantically and for SEO. I changed them all to actual hx tags.
I’ve used unordered and definition lists for the pricing – it could definitely be argued that a table is appropriate, but in either case it’s better than just a plain div (which holds no semantic value at all).
Don’t wrap a p in a div just to give a class or id, simply apply it to the p instead.
Don’t use break tags for creating spaces – use margins or padding instead.
I used an unordered list for the footer nav – I think you’ll agree it’s much cleaner
