Thread:Tlaqh1335/@comment-46173343-20200808190730/@comment-46173343-20200808195242

It's a 300 kb limit for the fire size. The theme designer literally just has a photo upload button, a "tile" checkbox, and a "fix" checbox to prevent the image from moving when scrolling. There might be a way to adjust things in source mode, but I'd have to take time looking into that.

It looks like the original background wallpaper was just a very wide image, and whoever uploaded it simply fixed it to the page, giving the illusion the picture was adjusted to fit the screen.