How to remove sidebar on single page 7.0

Hi all,

I've been having a hard time removing the sidebar on a single page on Squarespace 7.0.

I located the collection ID and added it to the code below, and then pasted this in the Page Header Code Injection under Advanced. But... no luck. Both the sidebar and the code are showing.

Could anyone help me out with this?

Here is the code:

/* Remove Main Nav */
body#collection-66617a3bd66c3246668fd5c2 nav#mainNavigation
{
  display: none !important;
}
/* Remove Secondary Nav */
body#collection-66617a3bd66c3246668fd5c2 nav#mainNavigation nav#secondaryNavigation {
   display: none !important;
}

Thank you in advance!

Update: Just refreshed my page hours later and it worked?! If anyone is trying this in the future, it *might* be different for different templates...I use Wells for reference.