When you cut the source on that page into a new html file and try to view it in mozilla (sorry i am only using 12) mozilla just copysblocks of it's own memmory space around the canvas - like randomly placed copies of partial scrollbars and the mozilla logo from the upper right corner. Once you add a little content to the div (as i used it for a page template) you find that mozilla places the footer over the header. After playing with it, i found that if you change the position from 'auto' to a percentage or to a pixel location it works. The funny thing, as i see it, is that w3c says themselves if the units of something are not specified it should be ignored - the value should be ignored. in their example the 'px' was not specified. This is why I believe mozilla would not work when i simply tried to set top and bottom to 100 rather than 100px. (I assume that in the case of a 0 value - the units are irrelevant or ignored.)

It could be a dup of bug 26584. Reassigned to Troy.

Yup, this is a DUP of 26584. As far as units go, the CSS2 spec says that a length identifier is required. The only exception is for a value of 0. That means '100' is illegal and '100px' is correct *** This bug has been marked as a duplicate of 26584 ***

Verified dup of #26584