Yes they're the same size, because in fact they're all the same image. The problem isn't with the image, it's with the code being used to display it. In all my other gadgets, the background image is being called in the gadget.html, but in the uptime gadget it's through the gadget.css. That's where the problem is, but when I tried messing with the code it wasn't working properly (because I don't know what I'm doing). 
