Different Background for Certain Page

I was helped by someone with placing a custom background on a couple certain pages a while ago, but now I removed one of the pages and re-created it to hopefully repair a problem I’d had on it. But now the original site background is behind the page. How can I place the custom background on the page again?
The custom CSS I was given to create the custom background for the particular pages is this:

body.page-id-8027, body.page-id-7959, body.parent-pageid-7959 {
    background-image: url(https://www.tnmartistry.com/wp-content/uploads/2019/05/Background-1-4.jpg);
}

The page I need help with: [log in to see the link]