title: Flutter change textfield underline Color
body: <p>I am trying to change the underline color of a textfield when it's inactive/not focused. I am not sure where to make this change, <code>InputDecorationTheme</code> is only changing the underline color for when it's selected. How do I achieve this?</p>
  
  <pre><code>inputDecorationTheme: new InputDecorationTheme(
            labelStyle: new  TextStyle(
                color: Colors.blue[200],
            ),
            hintStyle: new TextStyle(color: Colors.grey),
          ),
  </code></pre>
  
  <p>I am trying to change this color the textfield to a lighter grey when it's not selected/out of focus.</p>
  
  <p><a href="https://i.stack.imgur.com/3PtKr.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3PtKr.png" alt="enter image description here"></a></p>