This store is a Tmall store, and the store version used is at least a professional version. The standard version of the newly opened store can't do this.

This is the background of the store decoration-style selection-and then you can choose the background color or put the prepared background in it, so it's ok. If you do it yourself, use ps, with a larger width and a blank width of 950 in the middle, so it will have this effect. I hope it helps, and if possible, adopt it.