fix: remove weird scrollbars (#2391)

app/assets/stylesheets/application/components/_site_content.scss

@@ -6,7 +6,6 @@
 }
 
 .siteContent__main {
-  @include scrollbars(12px);
   flex: 1 1 auto;
   z-index:100;
   overflow-y:scroll;

app/assets/stylesheets/application/components/_site_header.scss

@@ -4,11 +4,6 @@
   flex: 0 0 auto;
   color:#fff;
   z-index:1000;
-  border-right:12px solid #efefef;
-
-  .browser-firefox & {
-    border-right: 15px solid #fafafa;
-  }
 }
 
 .siteHeader__inside {