How do I make all pages the same gradient color?

Site URL: https://fife-herring-ayhr.squarespace.com/

#siteWrapper {
  background-image: linear-gradient(to right top, #febdf3, #f8d0fc, #f5e1ff, #f7f1ff, #ffffff);
  }

That is the code im putting into the "custom css" section but it isn't changing anything on my site. I've tried doing this on each individual page with the style tags and without and still nothing. 

Am I using the wrong background ID? I'm using the BARBOSA template if that helps.

Thanks! 

What is access pasword?