Understanding cross-browser compatibility

Cross-browser compatibility is the practice of testing designs across all major browser systems and is important in Web design because you don’t just design Web sites for yourself, but for an entire audience on the Web. Because you have no idea which browser your audience uses, it’s essential that you test your designs in all the different systems to ensure that all the visitors to your Web site have the same experience.
The problem that Web designers run into with Web browsers is that each
browser system uses a different layout engine that renders CSS differently.
The difference in CSS rendering can sometimes make adjusting your CSS
styling to account for the different layout engines a challenge. Additionally,
not every layout engine supports all versions of CSS. Table 5-1 illustrates the
different layout engines, the browsers, and the CSS version it supports to

give you an idea of what you’re dealing with when it comes to the different
browser systems. More information on CSS versions, support, and validation
is in Book VI.