Styling thumbnails and images

I have googled and not found an answer to this though it seems like quite a common requirement.

I would like to put a 3px solid green border around my thumbnails and displayed images. Would I use the mask for this? If so what sort of image would I create?

EDIT: CSS seems to be the answer, baord wouldn’t let me delete the message.

Ed

Yes, you can do it in css..

Image masks are used to cut something out from images. You can do a black and white image what will be used for the masking. Everthing that is in black, will be cut from the images. Look at the default image mask pics that is in the package.

But for solid borders, css.