Fix navigation buttons visibility on mobile devices (#9569)

Author: SasLord

plugins/workbench-resources/src/components/Workbench.svelte

@@ -1122,8 +1122,10 @@
   }
 
   .hamburger-container {
+    position: relative;
     display: flex;
     align-items: center;
+    z-index: 1;
 
     &.portrait {
       margin-left: 1rem;