<h3> Here we get some text </h3>

<h3> Here we get some other text </h3>

<h3> Every Header is similar  </h3>
<h3>Let's Have some modifications </h3>

var headers = document.getElementsByTagName('h3');

headers[0].style.fontFamily ='Arial';

headers[1].style.color ='blue';

headers[2].style.border ='solid blue 1px';

headers[3].style.textAlign ='center';