which css style handles the click event on a button? other than hover

Question

I see this site that has a button, when I hover over it the background changes.

When I click on the button, the button shading inverts i.e. reacts to the click event.

Which CSS style is this? I know :hover is for hover, but what about a click?

Answer 1

CSS3 does handle activation events now (2013).

The :active pseudo-class is working on any css selector like BUTTONs, not just A tags.

CSS3 STYLE

p { margin: 2em; }
button { background-color: White; color: SteelBlue; }
button:hover { background-color: LightSteelBlue; }
button:active { background-color: SteelBlue; color: White; }

HTML5

    <p>
        <button>test button with :active pseudo-class</button>
    </p>

Demo: http://jsfiddle.net/wp86u/

See: http://www.w3schools.com/css/css_pseudo_classes.asp (content changed since Diodeus answer)