message: Fix overlap issue with Sidebar and Dismissable banner
  * Increase zIndex of Sidebar to be on top of the page
  As of now, the Sidebar is being overlapped by Dismissable banner component
  * Unset z-index of Dismissable Banner
  It inherits a z-index of 1400 from Material UI's snackbar component
diff: @@ -31,6 +31,7 @@ const useStyles = makeStyles((theme: Theme) => ({
  marginTop: -theme.spacing(3),
  display: 'flex',
  flexFlow: 'row nowrap',
  + zIndex: 'unset',
  },
  icon: {
  fontSize: 20,
  