Credo che tu abbia un po di confuzsione in testa ..
codice:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="it">
<head>
<title>Prova layout 2 colonne</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<link type="text/css" rel="stylesheet" href="style.css" title="Style" media="all" />
</head>
<body>
<div id="contenitore">
<div id="header"><h1>Titolo del sito</h1></div>
<div id="colsx">Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.</div>
<div id="coldx">Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh euismod tincidunt ut laoreet dolore magna aliquam erat volutpat. Ut wisi enim ad minim veniam, quis nostrud exerci tation ullamcorper suscipit lobortis nisl ut aliquip ex ea commodo consequat. Duis autem vel eum iriure dolor in hendrerit in vulputate velit esse molestie consequat, vel illum dolore eu feugiat nulla facilisis at vero eros et accumsan et iusto odio dignissim qui blandit praesent luptatum zzril delenit augue duis dolore te feugait nulla facilisi.</div>
<div id="footer">Lorem ipsum dolor sit amet.</div>
</div>
</body>
</html>
Questo lo salvi come Pagina.htm
mentre questo lo salvi nella stessa cartella come style.css
codice:
body {background:white; text-align:center; font-family:Helvetica, arial, sans-serif;}
div#contenitore {background:#F90; width:900px; margin:0 auto; text-align:left; }
div#header {background:#4A2C3E; height:5em;}
h1 {color:white; text-align:right; padding:1em 1em 0 0; font-family:Georgia, serif;}
div#colsx {width:630px; \width:650px; w\idth:630px; float:left; padding:10px;}
div#coldx {background:#060; width:228px; \width: 250px; w\idth:228px; float:left; padding:10px; border-left:2px solid white;}
div#footer {background:#999; clear:left; border-top:3px solid #4A2C3E; text-align:center; }