title: Remove the gray color border in android spinner
body: <p>Hi i have to develop one spinner app.
  here how can i remove the default gray color border on android spinner item..please help me.</p>
  <p><img src="https://i.stack.imgur.com/sPqvr.png" alt="enter image description here" /></p>
  <p>How can i remove the default border from this image.</p>