<!DOCTYPE html>
<html>
<body>
<h1>What Can JavaScript Do?</h1>
<p id="demo">JavaScript can change the style of an HTML element.</p>
<button type="button" onclick="myFunction()">Click Me!</button>
<script>
function myFunction() {
var x = document.getElementById("demo");
x.style.fontSize = "25px";
x.style.color = "red";
}
</script>
</body>
</html>