bottom padding to enable scroll to mark all as read (#1980)

* bottom padding to enable scroll to mark all as read

* 100vh fallback for mobile

p/themes/base-theme/template.css

@@ -630,7 +630,8 @@ br + br + br {
 #bigMarkAsRead {
 	display: block;
 	width: 100%;
-	padding: 1em 0;
+	padding: 1em 0 100% 0;
+	padding: 1em 0 100vh 0;
 	text-align: center;
 	font-size: 1.4em;
 }