title: Border radius to curve inwards?
body: <p>How can I have the border to curve inwards instead of outwards?</p>
  
  <p>For instance - this is curving outwards:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>header {
    position: relative;
    height: 300px;
    background-image: linear-gradient(#ff9d2f, #ff6126);
    border-bottom-left-radius: 50% 20%;
    border-bottom-right-radius: 50% 20%;
  }
  
  h1 {
    margin: 0;
    padding: 100px 0;
    font: 44px "Arial";
    text-align: center;
  }
  
  header h1 {
    color: white;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;header&gt;
    &lt;h1&gt;Header Content&lt;/h1&gt;
  &lt;/header&gt;
  
  &lt;section&gt;
    &lt;h1&gt;Section Content&lt;/h1&gt;
  &lt;/section&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I would like it to curve inwards, is it possible?</p>