fix: Mobile style fixes and improvements (#1459)

* fixes #1457 – check for matchMedia function before using it

* fixes: Depth issues
closes #1458

* fixes: Long breadcrumbs cause horizontal overflow

* fix: Improve tabs and overflow on mobile

app/components/Toasts/Toasts.js

@@ -34,7 +34,7 @@ const List = styled.ol`
   list-style: none;
   margin: 0;
   padding: 0;
-  z-index: 1000;
+  z-index: ${(props) => props.theme.depths.toasts};
 `;
 
 export default inject("ui")(Toasts);