Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p id="myP">This is a paragraph.</p>

<button type="button" onclick="myFunction()">Adjust font size</button>
 
<p><b>Note:</b> The fontSizeAdjust property is only supported in Firefox.</p>

<script>
function myFunction() {
    document.getElementById("myP").style.fontSizeAdjust = "0.58";
}
</script>

</body>
</html>