getElementBackdropFilter function
Returns the current backdrop-filter value (standard or prefixed).
Implementation
String? getElementBackdropFilter(Element element) {
final v = element.style?.backdropFilter;
if (v != null && v.isNotEmpty) return v;
final w = element.style?.getPropertyValue('-webkit-backdrop-filter');
return (w != null && w.isNotEmpty) ? w : null;
}