Fixed sidenav scroll not working

assets/css/sidenav.css

@@ -2,6 +2,7 @@
 
 .sidenav {
     height: 100%;
+    overflow-y: hidden;
     width: 300px;
     transform: translateX(-270px); /* change margin with JavaScript */
     position: fixed; /* Stay in place */
@@ -15,6 +16,7 @@
 
 .sidenav.sidenav-open {
     transform: translateX(0);
+    overflow-y: auto;
 }