Introduction to CSS (Cascading Style Sheets) with JavaScript - JavaScript by Example - page 557

Figure 14.13 External style sheets.
14.6.2 Importing with @import
You can also import CSS files with the @import rule. This rule allows you to import one
external CSS file into another by adding the @import rule in other external CSS files.
The format for doing this is:
FORMAT
@import url(externalfile.css);
EXAMPLE
<style type="text/css">
@import url(http://www.mystyles.com/style.css);
@import url(/stylesheets/.css);
h1 { color: blue }
</style>