[Sanda]

<style>
  .rounded {
    border-radius: 50px; 
    font-size: 50px; 
    height: 55px; 
    border: 1px solid black;
    margin: 20px;
  }

  .hidden {
    overflow: hidden;
  }

  .red {
    background-color: red;
  }
</style>
<div class="rounded"><div class="red">aa</div></div>
<div class="rounded hidden"><div class="red">aa</div></div>