Revert "Fix Web Component rustdoc-topbar position"

This reverts commit 2141095.

Author: RAIHERE

templates/style/_rustdoc-common.scss

@@ -81,7 +81,6 @@ div.rustdoc {
         }
     }
 
-    rustdoc-topbar,
     .mobile-topbar,
     #source-sidebar {
         top: $top-navbar-height;