Web pages are displaying as designed when using IE but incorrectly when using FireFox. And not small differences, major problems. Contols on the Left, in a Panel, are appearing centered and overlapping Labels. Labels with lengthy text (set in the code behind page) are not wrapping but extend off the page.

I am not sure how to fix these types of problem. If I knew generally what causes this to happen I would have a starting point but right now its all trial and error. I move things around, try this or that but am making it worse.

What are some good general rules to "live by" to keep all browsers happy? What TargetSchema should I generally use? What about Flow Layout vs Grid Layout? Absolute vs Relative? Properties (like Height and Width) vs using Styles.

Any links or documentation would be appreciated.