Sometimes declaration values are URLs relative to the style sheet
location. A special construct, standard in CSS level 2, allows you
to create a URL from the base URL of the current style sheet. For
example, the following declaration extends the path of the current
style sheet URL with
images/icon.gif
.
How to extend the path of the current
style sheet
imageURL: url(images/icon.gif);
This feature is very useful for creating
style sheets with images located relative to the style sheet
itself, since the URL remains valid even when the CSS is cascaded
or imported elsewhere.