JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
    <div class="rectangle"></div>
    <div class="egg"></div>
</div>

CSS

.wrapper {
    width:200px;
    height:100px;
    overflow:hidden;
    position:relative;
}
.rectangle{
   width:200px;
   height:100px;
   background-color:red;
}
.egg {
    width:200px;
    height:100px;
    border-radius:50%;
    background-color:#fff;
    position:absolute;
    top:56px;
    
}