In order to continue with the exercises in the chapter, you will need to understand the importance of web browser compatibility. All web browsers are different, and most of them handle HTML and Cascading Style Sheets (CSS) differently. It is not so much that one web browser is better than another or that one web browser is more accurate at rendering HTML or CSS. Rather, it's that CSS rules are often interpreted differently by software developers who designed these browsers. For web developers and designers, this can be very annoying, but an unfortunate and inevitable reality.
So, to make sure that the changes that you make to Moodle's theme files are the same or similar across most of the major web browsers, you will need to install various web browsers, such as Firefox, Internet Explorer, Chrome, Opera, Safari, and so on, and make sure that you remember to test your changes. You shall learn to install the required web browsers as you work through this chapter...