Adding a background image to specific pages with Fulton theme

We have tried to use this CSS to add a background image on our Fulton site, however, it does not work anymore (we used it on a previous site we created). We want to add a background image on specific pages on the site.

#collection-5d128f4ab097aa000189ca64 {
.content {
  background-image: url('https://static1.squarespace.com/static/5d0a859cd5a08f0001d0110a/t/5d1a6256602a0e0001f6c2cf/1562010198809/new_3C_watermark.png') !important;
  background-repeat: no-repeat;
  background-position: center left !important;
  background-size: cover;
}
.content-inner {background: none;}
}

@jonheymr Use CSS. with #collection.... is page ID that you want use background image.

 #collection-5d128f4ab097aa000189ca64 #page {
   background-image: url('https://static1.squarespace.com/static/5d0a859cd5a08f0001d0110a/t/5d1a6256602a0e0001f6c2cf/1562010198809/new_3C_watermark.png');
   background-repeat: no-repeat;
   background-position: center center;
   background-size: cover;
 }

That's what we were doing previously. That css does not work. That collection ID is for the page we are attempting to add the image to.

@jonheymr can you share site url?

The site is still in progress so it is not live yet, still private.

@jonheymr You can setup password and share site url

https://the-3c-homes.squarespace.com/ pw: 3Csquarespace

@jonheymr You can try (replace #collection...with your page id)

#collection-5d128f4ab097aa000189ca64 #siteWrapper {
   background-image: url('https://static1.squarespace.com/static/5d0a859cd5a08f0001d0110a/t/5d1a6256602a0e0001f6c2cf/1562010198809/new_3C_watermark.png') !important;
   background-repeat: no-repeat;
   background-position: center left !important;
   background-size: cover;
 }

Seems to work now with the collection ID