parseDesignDimension function
Parses a CSS dimension string (e.g. "10px", "100%", "540px") to a double.
Implementation
double? parseDesignDimension(dynamic value) {
if (value == null) return null;
final str = value.toString().replaceAll(RegExp(r'[a-zA-Z%]'), '').trim();
return double.tryParse(str);
}