CSS values specified in non-integer percentages are truncated as percentages, rather than being computed with the actual value and truncated at the pixel level as necessary. See attached test-case, showing the behavior for both 'width' and 'left'. This reproduces with 419.3 and the 9/26 WebKit nightly. This causes Safari layout problems on Google Calendar, which does portions of its layout using decimal percentage widths and positions (Google bug 513320). Also filed as rdar://4752325
Created attachment 10789 [details] simple test-case
We don't support decimal percentages right now except for font-size. The Length class (used for front end storage for values like left and width) just stores integer values (which ends up being fine for everything but percents).
*** This bug has been marked as a duplicate of 5164 ***