title: curved div with transparent top
body: <p>I'm trying to create transparent div full width and height around 500px using borders but i have trouble with creating this kind of curved shape.
  It should look like on the example image, the yellow shape.
  <a href="https://i.stack.imgur.com/HSByI.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/HSByI.jpg" alt="enter image description here"></a></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>.transparent_bg {
      width: 100%; 
      height: 485px;  
      background: transparent;
      border:solid 5px #000;
      border-color:#000 transparent transparent transparent;
      border-radius: 50%/200px 200px 0 0;
      transform: rotate(180deg);
      position: relative;
      overflow:hidden;
  }
  
  .transparent_bg:after {
      content: "";
      width: 100%;
      height: 485px;
      position: absolute;
      top: 0;
      background: red;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="transparent_bg"&gt;&lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I have included a link to my work until this moment but without success.</p>