HTML
CSS
JavaScript
HTML
<!DOCTYPE html>
<html>
<head>
<script src='http://libs.itshubao.com/jquery/2.1.3/jquery.min.js'></script>
</head>
<body>

<p>The first paragraph in body.</p>

<div style="border:1px solid;">
<p>The first paragraph in div.</p>
<p>The last paragraph in div.</p>
</div><br>

<div style="border:1px solid;">
<span>This is a span element.</span>
<p>The first paragraph in another div.</p>
<p>The last paragraph in another div.</p>
</div>

<p>The last paragraph in body.</p>

</body>
</html>
CSS

  

  

    
JavaScript

    
$(document).ready(function(){
  $("p:first-child").css("background-color","yellow");
});