HTML and CSS Reference
When deciding whether to use a recent CSS feature, it is important to consider how your
site will look without it. If the feature enhances the appearance of your site, such as the
CSS 3 border-radius property, you might want to start using the feature, even when it
is viewable by only a small percentage of your visitors. Time works in your favor, and as
people abandon old browsers, a greater number of your visitors can see the feature, which
enhances their experience on your site. This is the essence of progressive enhancement.
On the other hand, if your site depends on the feature and appears broken without
it, you need to carefully consider how well supported the feature is and whether there
are fallbacks or scripts you can make use of to increase this support, such as those listed
on HTML5 Polyfills. 1 There are often many ways to achieve the same result in CSS, so it is
a good idea to choose a method that is well supported by all major browsers for the key
elements of your site, such as the layout.