message: Add missing var for bootstrapmaterial theme. Fix for T4428.
diff: @@ -506,6 +506,7 @@ export class StylesManager {
  "$slider-color": "white",
  "$disabled-switch-color": "#9f9f9f",
  "$disabled-slider-color": "#cfcfcf",
  + "$body-background-color": "#ffffff"
  },
  };
  public static ThemeCss: { [key: string]: string } = {
  