The best way to do this, using CSS Grids, would be to create a div outside the #doc2 div which you would use as your header div. Just delete the div#hd from inside the #doc2 div, and you won't have that header at all.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<title>YUI Base Page</title>
<link rel="stylesheet" href="http://yui.yahooapis.com/2.7.0/build/reset-fonts-grids/reset-fonts-grids.css" type="text/css">
</head>
<body>
<div id="doc3" class="yui-t7"><div id="hd" role="banner">Header</div></div>
<div id="doc2" class="yui-t7">
<div id="bd" role="main">
<div class="yui-g">
<!-- YOUR DATA GOES HERE -->
</div>
</div>
<div id="ft" role="contentinfo"><p>Footer</p></div>
</div>
</body>
</html>