Remove Elements From One Page

I wrote about a month ago to the email address indicated, but never heard anything back, so here I am!

For my website, there is a particular page that I would like to remove the header image, both navigation bars, and footer for. However, when I try to accomplish this with CSS, it doesn’t work.

My website can be found here. The CSS that is not working is as follows:

.page-id-141474 .site-header { display: none; }

.page-id-141474 .site-navigation { display: none; }

.page-id-141474 .site-footer { display: none; }

I tried using CSS from a support forum to see if I could get the header to disappear from all pages, and that did work (but this is not what I’m hoping to accomplish):

body:not(.home) .entry-header{
display:none;
}

Thank you in advance for your help!

The page I need help with: [log in to see the link]