Fixes #286 - fix navigation flash during resize.

app/scripts/main.js

@@ -37,6 +37,7 @@
     body.classList.toggle('open');
     appbarElement.classList.toggle('open');
     navdrawerContainer.classList.toggle('open');
+    navdrawerContainer.classList.add('opened');
   }
 
   main.addEventListener('click', closeMenu);

app/styles/main.css

@@ -159,7 +159,7 @@ button.menu img {
           transform: translate(0, 0);
 }
 
-.app-bar, .navdrawer-container, main {
+.app-bar, .navdrawer-container.opened, main {
   -webkit-transition: -webkit-transform 0.3s ease-out;
           transition: transform 0.3s ease-out;
 }