ui + feature(header): issue #105 - User panel

- Transform it into HTML5 component detail + summary.
- Add/remove styles.
- Add "animation" on menu-header
- Make it clear for keyboard users + some accessibility.
- Refactoring, code moved.
- Add JS.

src/scripts/index.js

@@ -45,5 +45,4 @@ document.addEventListener('DOMContentLoaded', function (event) {
       rightMenu.classList.toggle('offsite-is-closed');
     })
   })
-  
 });