HTML and CSS Reference
Figure 1-2. The support tables at caniuse.com provide up-to-date information about CSS3
Web designers and developers tend to upgrade their browsers much more frequently than other users, who
might not even have the freedom to update because of policies imposed by the system administrators at their
place of work or study. Choosing whether to use a feature is a decision that only you can make as the designer. If
it's important to you that your design looks identical in all browsers, you'll be limited to whatever is supported by
the lowest common denominator among your target browsers. However, most people use only one browser, so
they won't see the difference—as long as you make sure that the design looks acceptable even in older browsers.
Also, many people are now used to seeing websites look different on mobile phones and tablets, so the overall
design is more important than pixel-perfect uniformity.
Not ■ CSS3 builds on the previous versions, preserving existing features and adding new ones. CSS doesn't
trigger an error if you use a feature the browser doesn't recognize. browsers silently ignore CSS properties and values
that they don't support.
So, How Do I Use CSS?
You normally style web pages by creating an external file called a style sheet , which contains a series of rules
identifying which parts of the page you want to affect and how they should look. Like HTML, CSS is written as plain
text. You don't need anything more sophisticated than a text editor, such as Notepad or TextEdit, to start writing