title: Flutter Layout Container Margin
body: <p>I have a problem with my Flutter Layout.</p>
  
  <p>I have a simple container with a Margin right and left of 20.0
  Inside this container i have another container.</p>
  
  <p>But this container does not fit to the parent container only on the left side.
  I dont know why this happens.</p>
  
  <p>Here is my Code:</p>
  
  <pre><code>  @override
    Widget build(BuildContext context) {
      return new Scaffold(
        backgroundColor: Colors.white,
        body: new Container(
          margin: new EdgeInsets.symmetric(horizontal: 20.0),
          child: new Container(
  
          )
        ),
      );
    }
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/KtN8B.png" rel="noreferrer">Screenshot of the Problem</a></p>