HOW TO make web pages "cross browser"
An oft repeated question on the online message-boards is how to make web pages render & behave the same in IE, Firefox and other popular browsers. This does not have an easy answer. The incompatibilities are due to the browser wars & the host of non-standard HTML & scripting features that the different browsers have introduced.
In my opinion, developers can build cross browser web pages by being aware of the standards that popular browsers commonly follow & sticking to them.
I have found these resources useful while building cross browser web pages -
HTML 4.01 / XHTML 1.0 Reference
CSS 2.0 Reference
QuirksMode.org Browser Compatibility Tables
JavaScript and Browser Objects Quick Reference
Migrate apps from Internet Explorer to Mozilla
Related links:
HOW TO easily verify your website design in different browsers/OSs