How to change color of html in page 2 by clicking the button in page 1

**page1.html**

     <button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
  document.querySelector(".example").style.backgroundColor = "red";
}
</script>

**page2.html**

<h2 class="example">A heading with class="example"</h2>

The background color of the h2 tag with class named example won't change after clicked the button in page 1.