.umb-overlay-backdrop {
   position: fixed;
   width: 100%;
   height: 100%;
   background-color: rgba(255, 255, 255, 0.50);
   z-index: @zindexOverlayBackdrop;
   top: 0;
   left: 0;
   animation: fadeIn 0.2s;
}

.umb-drawer-is-visible .umb-overlay-backdrop {
    left: @drawerWidth;
}