margin property Null safety

1. baguette
2. CardWidget
3. CardWidget
4. margin property

CardWidget class

1. Constructors
2. CardWidget
3. Properties
4. borderColor
5. borderRadius
6. borderShadow
7. child
8. color
9. hashCode
10. height
11. key
12. margin
13. padding
14. runtimeType
15. width
16. Methods
17. build
18. createElement
19. debugDescribeChildren
20. debugFillProperties
21. noSuchMethod
22. toDiagnosticsNode
23. toString
24. toStringDeep
25. toStringShallow
26. toStringShort
27. Operators
28. operator ==