Since this is a background css image its probably best to just upload a larger image rather than a small one that will adjust. If you add “background: size:” your image will adjust with no problem when the browser is wide, but when its set at a smaller size the image won’t cover the entire space and it won’t look right. Which is why always recommend just adding a large image that can cover any browser size….or an image that can be repeated.
To set it to no repeat – background-repeat: no-repeat;
To center – background-position: center;
Image adjustment – background-size: 100%; …or background-size: 100% 100%; – this covers the top and bottom …..or background-size: cover; <-- Recommended if you're going to go this route
You can do a Google search for Responsive Css Background Images for more info on different ways to do it.