Removing div acting as header on select pages

I’m a little new to wordpress and trying to figure this out. I haven’t been able to find an answer to my specific issue, so I’m hoping someone can help.

The header to my site displays on all pages, but I want to hide it on a select few pages.

The header is not plugged into the theme as a “header” (header.php) and is instead a separate div at the top of the page. The same thing goes for the footer. I’d like to remove both from select pages.

I’m using a child theme, and here’s my best guess on what I should do:

Make a duplicate css file hiding the top div, and somehow tell the pages I want to instead grab that css file. I know how to hide the div and make a duplicate css file, but I don’t know how to assign that duplicate css to just the pages I want.

Here’s the site for reference
Any help would be greatly appreciated.

Thanks!