Link to the wp appearance / background option?

I’m creating a custom dashboard screen for users on a multisite.

I’d love to know how to create a link to the admin/appearance/background option?

I tried creating a hyperlink like this: “themes.php?page=custom-background” but it just takes me to a 404 not found.

If I use the full path: “http://mainsite.com/sample-blog1/wp-admin/themes.php?page=custom-background” then it works, but I don’t want to have to create a special link for every subsite owner :slight_smile:

Thanks