Blank pages when printing

If you set a header image in the customizer, then when you go to print a page with a header image, the entire page is blank.
It’s because the body tag gets the CSS class header-image. BUT the theme’s CSS file contains this code:

form, button, input, select, textarea, .header-image, .navbar-collapse, .main-navigation, a.readmore, .page-links, .edit-link, .post-navigation, .posts-navigation, .wp-pagenavi, .page-links, .pagination.navigation, .site-content .widget-area, .comments-pagination, .comment-respond, .comment-edit-link, .comment-reply-link, .comment-metadata .edit-link, .pingback .edit-link, .site-footer {
    display: none;
}

Most importantly it includes header-image, which is the CSS class applied to the body tag, not the actual header image (which is probably what was intended.) I think header-image should be removed as a CSS selector in that bit of code.

A workaround is to add this custom CSS to the theme:

@media print{
	body.header-image{
		display:block;
	}
}