[Solved] How to create the following image as header background in HTML5 and CSS3?

by 


.container {
  width: 100%;
  height: 400px;
  background-color: lightgray;
  position: relative;
  overflow: hidden;
 }

.inner {
  position: absolute;
  background-color: black;
  top: -200px;
  left: -50%;
  height: 400px;
  width: 200%;
  border-radius: 50%;
 }
<div class="container">
  <div class="inner">
  </div>
 </div>

solved How to create the following image as header background in HTML5 and CSS3?