refactor: remove duplicate crosses font-face declaration

The crosses font is already defined in app.css which loads globally,
so the duplicate in rosenkranz.css is unnecessary.

src/lib/css/rosenkranz.css

@@ -1,11 +1,3 @@
-@font-face {
-  font-family: 'crosses';
-  font-style: normal;
-  font-weight: 400;
-  font-display: swap;
-  src: url(/fonts/crosses.woff2) format('woff2'),
-       url(/fonts/crosses.ttf) format('truetype');
-}
 @font-face {
   font-family: 'LibertineMinimal';
   font-style: normal;