Hello Reader's if you want to change css of any div or section or iframe with just a single click then javascript offers you to do this in real time. Lets see how to change background color of an ifram using just a single click

<iframe src="JavaScript:'content'" style="height:100px"></iframe>

<input type="button" onclick="ChangeBGColor()" value="click me">

In the code above the button will change the background color of Iframe when clicked.

Now the JS for this event will go like this:-

<script>
  function ChangeBGColor() {
    var iframe = document.getElementsByTagName('iframe')[0]
    var doc = iframe.contentWindow.document
    doc.body.style.backgroundColor = 'green'
  }
</script>

Now on loading the page when user will click the button.