How to hide header image on blog feed?

Site: tyleraldridge.com
Theme: Hemingway

Okay, so I’m trying to have the header image displayed on the landing page only (which is a page and not the post feed). The post feed is on the “What” page of my site and I don’t want the header image displayed there. To remove the header image on all the other pages I added a <?php if( is_home() || is_front_page() ) :?> argument to header.php. To remove the header from SINGLE posts I added this to my CSS:

.single .header-image {
 display: none;
}

To remove the header image from my post feed (‘What’ page on my site) I thought this would work:

.blog .header-image {
display: none;
}

But it doesn’t do anything. I’ve tried different things like

.blog custom-background has-featured-image .header-image {
display: none;
}

or

body.blog .header-image {
display: none;
}

And those do nothing either. Kinda stumped here. Can anyone help me out?