Add box-sizing: border-box to css reset. In a variety of places, there
was content overlap, coming from where padding was set with a width of
100%. Setting box-sizing: border-box in the css reset allows for
padding to be set with a 100% width.
Bug: Issue 6372
Change-Id: Id177a5c7b000b7bfb2cce456e4834104e8c7e912