Remove header/navigation from top of page

I am trying to build a landing page and completely limit the header/footer navigation so people don't leave the page before taking advantage of my offer. 

I have tried putting #block-5dc09a085727892a9868f1f7 {display: none} in the custom CSS panel and 

<style>
  .Header.Header--top,
  .Header.Header--bottom,
  .Footer {
    display: none;
  }
</style>  

in the advanced page settings but neither of them make my navigation disappear. 

my site is www.fpg.com and the one I'm trying to target is fpg.com/masterclassb 

Any help would be much appreciated.

Add to Home > Design > Custom CSS

/* remove header */
body#collection-5dc099f9d2910734b3174bb3 header.Header.Header--bottom.Header--overlay {
    display: none;
}
/* remove top bar */
body#collection-5dc099f9d2910734b3174bb3 header.Header.Header--top {
    display: none !important;
}
/* remove footer */
body#collection-5dc099f9d2910734b3174bb3 .tweak-footer-show .Footer {
    display: none;
}