title: Circle with inset shadow and gradient
body: <p>I wonder how to achieve the following effect. A circle with an inset shadow that also has a gradient.</p>
  
  <p><a href="https://i.stack.imgur.com/LhFZV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LhFZV.png" alt="enter image description here"></a></p>
  
  <p>I managed to get an inset shadow but with even color. I would need a gradient on the inset I think.</p>
  
  <pre><code>Container(
      height: 300,
      decoration: BoxDecoration(
        shape: BoxShape.circle,
        boxShadow: [
          BoxShadow(
            color: Color(0xffa3b1c6), // darker color
          ),
          BoxShadow(
            color: Color(0xffe0e5ec), // background color
            spreadRadius: -12.0,
            blurRadius: 12.0,
          ),
        ],
      ),
    ),
  </code></pre>
  
  <p>Gives the following:</p>
  
  <p><a href="https://i.stack.imgur.com/QRUq7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QRUq7.png" alt="enter image description here"></a></p>