Same background for all pages automatically

How do I set all pages to have the same background color or pattern so when I create a new page it will be automatic.

That feature is not onboard yet with Sparkle, but you can create the one page with the background you intend to use across all your pages and then duplicate it, which is the middle icon at the bottom left of your left-hand column.

This has been on the wish list of many users here for a long time. Maybe it will come in a future version of Sparkle.

I had already written something about this:

Page Background is a “per page” setting. You can not change all pages at the same time, with one action. Especially when you have a pattern.
What you could do is using a color. Reserve one color (from the dots) for the background. You have to edit each and every page and apply this color (only one time). Now, when you change it in the selector panel, it is synchronized and appears as background on all pages.

Mr. F.