Make sure font size in inputs is 16px

Some browsers (e.g. Safari on iOS 6) still zoom on inputs with smaller
font size. Also, make sure header font is the same size (so that it's
consistent with the search input).

Change-Id: Ib01c8579ba7c34054bec2d4d67ceda91f4e421dc
Merge "Make sure font size in inputs is 16px"