fix: fit mobile toolbar and make scrollable (#6270)

Co-authored-by: dwelle <luzar.david@gmail.com>

src/css/styles.scss

@@ -530,6 +530,7 @@
   // (doesn't work in Firefox)
   ::-webkit-scrollbar {
     width: 3px;
+    height: 3px;
   }
 
   ::-webkit-scrollbar-thumb {
@@ -567,8 +568,8 @@
   }
 
   .App-toolbar--mobile {
-    overflow-x: hidden;
-    max-width: 100vw;
+    overflow-x: auto;
+    max-width: 90vw;
 
     .ToolIcon__keybinding {
       display: none;