Set a higher z-index on the menu to avoid it being overlapped by other page elements.

canard/style.css

@@ -3616,9 +3616,7 @@ a {
 	}
 	.main-navigation {
 		float: left;
-	}
-	.main-navigation {
-		z-index: 1;
+		z-index: 99;
 	}
 	.main-navigation > div {
 		display: block;