Cross browser Issues

Let's make a short list here:

1) box model

2) float issues (ie7), the order of the elements make a difference as to whether ie7 can properly float them.

3) select boxes bleeding through

4) memory leaks

5) sometimes, even line breaks are treated differently, depending on whether you make them XHTML compatible

6) ie doesn't support rounded corners or even box shadows

7) firefox and gecko based browsers, pass by null references uninterupted vs IE does not (ie often stops in it's tracks)

8) Page layout issues...

9) widths artificially constrained causing things to line break where they shouldn't

10) I could probably cover the whole page with miscellaneous ie issues

11) Did i mention that container divs with scrollbars can't maintain their shape if inside elements are inline elements declared with display: block;

12) Someone could probably write a whole book about the positioning, margins and padding bugs.