Well on my site I use a background image. I can't remember what the image size is, but when I look at the site on my 1920x1080 monitor, it looks perfect. But when I use a different PC or Mac with other resolutions, the image doesn't fit perfectly. Some resolutions you can only see about half of the background image, and some resolutions the background image is shifted far to the right, etc etc. How can I fix this to fit all resolutions perfectly and center?