Remove menu on one page (homepage)

I’m trying to create an acknowledgement of Country to display on my homepage and would like to remove the menu / header hr for that one page. I have tried

.page-id-323 .primary-menu .expanded-menu {
display: none !important;
}

with no success so far. I’d really appreciate any nudges in the right direction.

[At the moment my homepage is set to my “about” page. This will be updated once I figure out how to get the acknowledgement looking a little better.]

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