<html>
  <style>
    body {
      font-family: Roboto;
      font-size: 50px;
      font-weight: bold;
      color: black;
    }
    div {
      width: 50px;
      height: 50px;
    }
    #green {
      background-color: green;
      margin-bottom: 50px;
    }
    #yellow {
      background-color: yellow;
      margin-top: 50px;
    }
  </style>
  <body>
    <div id=green></div>
    <span>Hello world</span>
    <div id=yellow></div>
  </body>
</html>