<div class="bg">
  
</div>
.bg {
  width: 350px;
  height: 450px;
  border:2px solid black;
  position:relative;
  overflow:hidden;
}
.bg:before {
  content:'';
  position:absolute;
  background: #2126A6;
  width: 133%;
  height: 150px;
  border-radius:50%;
  left: 50%;
  transform: translate(-50%,-50%);
}

External CSS

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External JavaScript

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