outline

This property is a shorthand form that sets all outline properties at once. Outlines resemble borders but take up no additional space, and can be set to a shape different from that of the image, form field, or other element to which they are applied. Outlines are drawn over an item, rather than around it, thus causing no reflow. The shorthand syntax is as follows:

outline: outline-color outline-style outline-width;

While outlines are similar to borders, their individual sides cannot be set. All outline properties, both specific and shorthand, apply to the whole outline.

Examples

p:hover {outline: dashed;}
.test {outline: green solid 10px;}

Browser and CSS Support Notes

CSS2
No IE support
Nav 6, 7 use a proprietary style
Opera 7

TIP Mozilla also supports an outline style with a proprietary syntax: -moz-outline.