Description

This pseudo-class matches any element that’s in the process of being activated. It would apply, for instance, for the duration of a mouse-click on a link, from the point at which the mouse button’s pressed down until the point at which it’s released again. The pseudo-class does not signify a link to the active, or current, page—that’s a common misconception among CSS beginners.

Compatibility

Internet Explorer 5.5 and 6 incorrectly apply this pseudo-class to links that have keyboard input focus—a state that should be matched by :focus, which those browsers do not support.

Internet Explorer versions up to and including 7:

• Apply :active only to HTML a elements that have an href attribute.
• Ignore :active unless it’s the last part of a pseudo-class chain.

In Internet Explorer version 8 the manipulation of elements with negative z-index is buggy when used in conjunction with :hover or :active rules (source James Hopkins).