Tryit Editor v2.9

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

<p>
  <a href="../html/default.asp.html">HTML</a><br>
  <a href="../css/default.asp.html">CSS</a>
</p>

<p>Click the button to add a red border to the first link in the document.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    document.links[0].style.border = "5px solid red";
}
</script>

</body>
</html>