title: Change the default border color of TextFormField in FLUTTER
body: <p>Unable to change the default border color when TextFormField is not active. When TextFormField is not active this shows DarkGrey-Border color. So, how to change that.</p>
  
  <p><a href="https://i.stack.imgur.com/VI1rW.png" rel="noreferrer"><img src="https://i.stack.imgur.com/VI1rW.png" alt="enter image description here"></a></p>
  
  <pre><code>Theme(
                data: new ThemeData(
                  primaryColor: Colors.red,
                  primaryColorDark: Colors.black,
                ),
                child: TextFormField(
                  decoration: new InputDecoration(
                    labelText: "Enter Email",
                    fillColor: Colors.white,
                    border: new OutlineInputBorder(
                      borderRadius: new BorderRadius.circular(25.0),
                      borderSide: new BorderSide(),
                    ),
                    //fillColor: Colors.green
                  ),
                  validator: (val) {
                    if (val.length == 0) {
                      return "Email cannot be empty";
                    } else {
                      return null;
                    }
                  },
                  keyboardType: TextInputType.emailAddress,
                  style: new TextStyle(
                    fontFamily: "Poppins",
                  ),
                ),
              ),
  </code></pre>