wpt eliminates post/page category classes

i am using css to hide post titles for 1 category:

.category-in-memoriam .entry-title 
{
   display: none!important;
}

which works as expected in desktop:

<article id="post-5817" class="post-5817 post type-post status-publish format-standard hentry category-announcement category-in-memoriam">
	<header class="entry-header">
				<h1 class="entry-title">Tim Evans</h1>

but not in mobile, as wpt replaces the article tag, containing the classes, with a div:

.category-in-memoriam .post-title 
{
   display: none!important;
}

<div class="post section post-5817 post-name-tim-evans post-author-3 single not-page no-thumbnail no-thumbs">
	<div class="post-page-head-area bauhaus">
		<h1 class="post-title heading-font">Tim Evans</h1>

unsat:-\

• This topic was modified 5 years, 6 months ago by airdrummer.

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