There are so many browsers and version of theses browsers that I became harder to create HTML that will run on all the possibles combinations. You need the appropriate tools to help you to debug.
There are few application and plugins you need to try :
- Markup Validation Service (http://validator.w3.org/) : to validate your (x)html page.
- Internet Explorer Developer Toolbar (http://www.microsoft.com/downloads/details.aspx?FamilyID=e59c3964-672d-4511-bb3e-2d5e1db91038&displaylang=en) : Microsoft Firebug alternative : to debug html, css ...
- Install multiple versions of IE on your PC (http://tredosoft.com/Multiple_IE) : Install more than one version of IE on your PC.
- CSS Formatter and Optimiser (http://floele.flyspray.org/csstidy//css_optimiser.php?lang=en) : a nice CSS formatter and optimiser.
Theses are the tools that I'm using to debug the main page of Glassfish. Even with that.. it's hard :)