This entry best viewed in Firefox 3
Gulp, looks likes it is back to 1999 again and testing on yet another browser. For the past couple years web developers have had it a little bit easier with CSS and by using Microsoft’s conditional comments were able to test for Internet Explorer versions 5, 5.5, 6, and 7. Firefox 2 worked almost the same between Windows and Linux/Mac as long as you set the initial font size somewhere near the top (on the body element) of the CSS style sheet. Safari on Mac uses the KHTML rendering engine, so testing for that was as easy as opening the web page in my window manager, Konqueror. At least (so far) it has been fairly easy to run two instances of different Firefox versions simultaneously and with all the cool new features supported in Firefox 3 it will be worth it to use them where possible.
I’ve already stopped using ems as a relative unit for layout and sizing and have gone back to pixels because of the zoom for IE7 that works like Opera. It makes sense, after all a pixel is a relative unit too and the user agent should rescale pixel values according to the recommended reference pixel and not rely on the developer to markup HTML/CSS with not as user friendly ems or percentages.