fix style of grw-side-contents-sticky-container

packages/app/src/styles/_layout.scss

@@ -68,7 +68,6 @@ body.growi-layout-fluid .grw-container-convertible {
   position: sticky;
   // growisubnavigation + grw-navbar-boder + some spacing
   top: calc(100px + 4px + 20px);
-  margin-top: 5px;
 }
 
 .grw-fab {