Overflow:hidden doesn't seem to work together with W3.CSS
<ul>
<li><p>If I apply the css attribute <code>overflow:hidden</code> to the body, it will
works as expected. See <a href="http://www.bootply.com/w4LViM0ZzV" rel="nofollow">bootply</a>.</p></li>
<li><p>But if I include CSS3 and add <code>body {overflow:hidden;}</code>, it will
not work and I will be still able to scroll. See <a href="http://www.bootply.com/gVLJncuM6j" rel="nofollow">bootply</a>.</p></li>
</ul>

<p>Why is CSS3 overwriting the <code>overflow:hidden</code> attribute? And how can I use CSS3 and <code>overflow:hidden</code> together? </p>