Centering Images in Firefox?

So, I got a new widescreen monitor today, and I was curious if there was any way (via a script of some kind, add-on or whatever) to have images in a tab load in the center of the screen rather than justified to the left, as is the default. If anyone knows of a way to go about doing this, I would greatly appreciate it. Thanks!

>firefox still has no functionality without extensions

But it does have extensions unlike other browsers :3