How do I give text or an image a transparent background using CSS

Question

I want to select and set up a background image for the home page but however, despite the width being filled, the height is not by getting the image from the beginning of the screen. Is there a shortcoming in the code? Have I been missing the standard for images on flutter? Is there a difference of the screen resolutions depending on a person's mobile phone and do the images scale accordingly?

class BaseLayout extends StatelessWidget{ 
@override 
Widget build(BuildContext context){ 
return new Scaffold( 
body: new Container( 
child: new Column( 
mainAxisAlignment: MainAxisAlignment.start, 
children: [ 
new Image.asset("assets/images/bulb.jpg"
) 
]
)
)
);
}
}

Answer 1

In order to ensure that your image has filled your entire screen, you could try to use a Decoration Image with a fit of BoxFit.cover for example:- 

class BaseLayout extends StatelessWidget{ 
@override 
Widget build(BuildContext context){ 
return Scaffold( 
body: Container( 
decoration: BoxDecoration(
                image: DecorationImage(
                  image: AssetImage("assets/images/bulb.jpg"), 
                        fit: BoxFit.cover, 
), 
), 
      child: null /* add child content here */, 
),
);
}
}