Relative Font sizes in CSS
Unless there's some new CSS3 feature I am unaware of, I find the font-size's being pixel based a bad thing.
While using JQueryMobile with Cordova or PhoneGap, devices with high density screens have all the UI elements a little to small to interact with. I went to adjust them using @media styles for DPI -- but was saddened to see that all 25+ font-size styles were in PX and could not be affected by adjusting the BODY's font size.
I thought that even with browser's support for "zooming" it was still best practice to use % or EM sized fonts...