CODE EXAMPLE FOR HTML

center iframe

<div class="iframe-container">
  <!--iframe link is the link to the jsfiddle-->
  <iframe src="https://jsfiddle.net/8z9s1t6x/2/"></iframe>
</div>

<style>
  .iframe-container {
		text-align:center;
  		width:100%;
  }
</style>