title: Set border size
body: <p>I want to make the border of a borderpane more round and bold.</p>
  
  <p>I tested this code:</p>
  
  <pre><code>bpi.setStyle("-fx-background-color: linear-gradient(to bottom, #f2f2f2, #d4d4d4);"
                  + " -fx-border: 12px solid; -fx-border-color: white; -fx-background-radius: 15.0;"
                  + " -fx-border-radius: 15.0");
  </code></pre>
  
  <p>I get this result:</p>
  
  <p><img src="https://i.stack.imgur.com/oT69J.png" alt="enter image description here"></p>
  
  <p>How I can fix this?</p>