Flatiron Custom CSS for different background color on one page

Site URL: http://sydney-friedman.com/

I'm trying to change the background color of the body of one page. I'm trying to make it a light grey since the images on top will have white backgrounds that I want to appear. What code do you recommend I use in the Custom CSS ? The template is Flatiron.

Thanks!

Add to Design > Custom CSS (this code for About Page)

/* about page background */
body#collection-580e5f7a46c3c44223165db2 {
& {
    background-color: lightgrey;
}
#navigator {
    background-color: lightgrey;
}}

To apply for other pages, you can replace body#...db2 with Page ID. See how to find Page ID.