As a simple example, we’ll use the CSS feature text-emphasis, which is to be newly introduced in CSS selectors level 4 and can only be used experimentally in some web browsers (at the time of print) using web browser prefixes. This CSS feature allows you to highlight the emphasis of text with a different color and style, for example, with circles, points, or triangles. However, this isn’t about the feature in detail, but about the browser prefixes. Here’s an example:

h1 {
    text-emphasis: filled double-circle blue;
} 

This is used to particularly highlight the h1 heading with blue double circles if the web browser can handle the CSS feature text-emphasis, which wasn’t the case when this book went into print. However, because some web browsers have already implemented this CSS feature experimentally, you can use and test browser prefixes as follows:

...
h1 {
    -moz-text-emphasis: filled double-circle blue;
    -webkit-text-emphasis: filled double-circle blue;
    text-emphasis: filled double-circle blue;
} 

Listing 11.14     /examples/chapter011/11_6/css/style.css