Change background image css on a single page

Hi !
I am currently working on a website, and I have some trouble with the background image.
I have one page that have an excessive height, and the background image get zoomed a lot at the bottom of that page.

Do you know a solution to modify the theme configuration on that single page ?

Sorry for my english, I’m still learning.

Hi,

Can you share your site URL here?

Regards,
Awan

No, sorry but I can’t, i’m working on a local server.
I can provide screenshot if it help.

Ok nevermind, I have a solution : in the custom CSS I writed

body {
   background-image: url("/wordpress/wp-content/uploads/2017/05/Fiche-A4-Dégradé-Verso.jpg")  !important;
   background-repeat: no-repeat;
   background-position: center bottom;
   background-size: 100% auto; 
}