(The red line down the right side of the page is set at 800px.)
Font sizing/Div sizing tests
This is the default, 16px setting at a 50em width.
This is the default, 16px setting at a 800px width. This should be equivalent to the above div.
This is the default, 16px setting at a 800pt width.
Font size differences (differences when size is set on the div itself)
This is Verdana (set on the div) with no font size changes and div set to 50em.
This is .8em Verdana on the div set to 50em. (800px * 80% = 640px)
This is 80% Verdana on the div set to 50em. (Should be equal to the div above.)
This is 12pt Verdana on the div at 50em. Since 12pt is equal to 16px, this is equal to original divs.
This is 12px Verdana on the div at 50em. (600px wide since 12px is now equal to 1em. 12*50)
This is 12px Verdana on the P element with the div still at 50em. (Back to the 800px width since the div is not given a font size.)
Changing the font size of the base browser default scaled the proportional units of measure as expected. Changing the font family from the browser's default Times had no effect on the div sizing. All em unit sized divs remain based on the pixel size set (default 16px) no matter which font is specified as the default.