Allow zoomed in images to expand up to edges of window/page

Currently when you zoom in on an image, it doesn't change the shape/size of the viewing pane which is set based on the original image's aspect ratio when it's zoomed out to fit. So for example if you view a comic that is really tall and not very wide, when you zoom in to read it the viewing pane doesn't expand the width at all and you're left trying to read the comic in a tall and narrow slice on the screen with the rest of it all blank. You can click and drag left and right to scroll but it should expand the viewing area to minimize that so you only need to scroll up and down.

As an example look at an image like this: https://beta.furrynetwork.com/artwork/66712/clubs-of-fa/fullscreen

On most screens this image will be constrained vertically to fit and leave a lot of empty area on the sides when viewed full screen, but when you zoom in the width doesn't increase forcing you to zoom left and right even though there's tons of space on the screen!