HORIZONTALLY CENTER DIV
Run 
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>CSS</title>

<style>
   
  .outer{
        display: flex;
        align-items: center;
        justify-content: center;
      }
      .inner {
        width: 300px;
		border: 3px solid blue;
        height: 100px;
      }
     h2, .inner {
	   text-align: center;
	   }
</style>
</head>
<body>
    <h2> horizontally centered div using CSS </h2>
	<div class="outer">
	  <div class="inner">Horizontally centered </div>
	</div>
</body>
</html>