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

shared/styles/theme.js

@@ -101,6 +101,16 @@ export const base = {
     desktop: 1025, // targeting devices that are larger than the iPad (which is 1024px in landscape mode)
     desktopLarge: 1600,
   },
+
+  depths: {
+    sidebar: 1000,
+    modalOverlay: 2000,
+    modal: 3000,
+    menu: 4000,
+    toasts: 5000,
+    loadingIndicatorBar: 6000,
+    popover: 9000,
+  },
 };
 
 export const light = {