Set list-style-image size

How do I restrict the size of an list-style-image item? Most of the time the URL is from a remote server (that is out of my control).

This is for a Firefox extension, but it is a CSS issue, so I don’t have to worry much about cross-browser support, but I am restricted to using a list-style-image.

What do you mean restrict its size? Restrict during upload?

I don’t think you can specify the size of the image in css. I should grab them and resize and put in your webspace.