fix menu id

js/customElements/header.js

@@ -14,7 +14,7 @@ class Header extends HTMLElement {
                     <jl-svg data-name="banner"></jl-svg>
                     </div >
                 </div >
-                <jl-main_menu id = "mainMenu" data-title = "${pageTitle}"></jl-main_menu>
+                <jl-main_menu id = "mainmenu" data-title = "${pageTitle}"></jl-main_menu>
             </header>
         `;
     }