Verifying and Improving Cross-Browser Rendering
Cross-browser rendering simply means how a page renders in different browsers. Generally, you want a Web page to render identically in all modern browsers. Sometimes getting an absolutely identical rendering requires more work than it’s worth, so what you should really concentrate on is getting an acceptable rendering across all common browsers.
Methods that you might use to obtain an absolutely identical rendering might cause problems when any of the browsers that are involved are updated or change versions, and you would need to repair whatever you did to obtain the identical rendering.
The solution is to make sure that your pages are valid and accessible, and that they render well across major browsers. ...