Browser Compatibility Tutorial

This excellent tutorial, and its assorted tools, explains why you may be seeing browser display errors and recommends steps to avoid these problems.
The Browser Photo service helps you know if you have browser display errors by showing you actual snapshots of your page under different browsers, computers, and screen resolutions.

HTML Toolbox shows you whether display errors are due to browser compatibility problems or HTML code errors. HTML Toolbox has a one-click repair feature that repairs most coding errors, but in some cases your display problems may be due to other factors. Click here for the site.