JSFiddle - React, Tailwind, and code Playground

HTML

<div class="circle curves"></div>
<div class="roundedCorner curves"></div>
<div class="curves"></div>
<div class="oval curves"></div>

CSS

div {
  height: 300px;
  width: 300px;
  background: #346DA2;
  margin: 150px auto;
}
.circle {
    border-radius: 50%;
}
.oval {
  border-radius: 50%;
  height: 150px;
  width: 300px;
}
.roundedCorner {
  border-radius: 25%;
}