JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
  <div class="test">
    
  </div>
</div>

CSS

.test {
  background: yellow;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: auto;
}

.wrapper {
  background: #000;
  display: inline-block;
  border: 10px solid #000;
  border-top-right-radius: 100px;
  border-top-left-radius: 100px;
}