Fix for # 1717 [2].

Author: ivan-nginx

source/css/_common/components/sidebar/sidebar.styl

@@ -40,4 +40,4 @@
 @import "sidebar-blogroll";
 @import "sidebar-nav";
 @import "sidebar-toc";
-@import "sidebar-dimmer";
+@import "sidebar-dimmer" if hexo-config('sidebar.onmobile');