JSFiddle - React, Tailwind, and code Playground

HTML

<div class="shape"></div>

CSS

.shape{
    background: #074b7e;
    width: 300px;
    height: 150px;
    overflow: hidden;
    position: relative;
 }
 
 .shape:before{
     content: '';
     width: 150px;
     height: 150px;
     background: #fff;
     position: absolute;
     top: 0;
     right: -75px;
     border-radius: 100%;
 }