Remove sidebar navigation in Supply for Product pages

Hello. I am using the Supply template , and I would like to remove the navigation menu and sidebar on the product page only. I have tried the following, and whilst the navigation menu is removed, there is a big empty space left where it was.

 <style>
      #header { display: none !important; }
  </style>

I am trying to remove the sidebar space and make the content fill the entire width of the page. I have tried a number of different things including the following but I'm having no luck with anything.

  <style>
       #folderNav, #primary-nav, #folder { display: none !important; margin: 0; padding: 0; }
       #content { width: 100% !important; }
       #main { width: 100% !important; }
       </style>

I can do it on normal pages, but not on the product page for some reason.

Any ideas? Thanks.