tweaks

Added the minimum HTML that i like to use from the html5 boilerplate project above the BODY tag - https://github.com/h5bp/html5-boilerplate/blob/master/src/index.html

margin:0 and padding:0 can usually pretty safely be applied to everything to avoid having to define these specific rules 500 times.

When defining zero as the value in CSS rules the unit does not need to be included.

the box-sizing should be applied to everything as well - http://www.paulirish.com/2012/box-sizing-border-box-ftw/

BR tags should not be used to create white space. Use margin and/or padding instead, I prefer EM units so that the margin space will be relative to font size - http://line25.com/articles/youre-doing-it-wrong-common-html-tag-misuse