Sorry for the technical problem, here is my code:
1.index.html
<head>
<title></title>
<link href="style.css" rel="stylesheet" type="text/css" />
</head>
<body class="twocolumn">
<div id="header">Some content</div>
<div id="left">Some content</div>
<div id="center">Some content</div>
<div id="footer">Some content</div>
</body>
</html>
2. style.css
@charset "utf-8";
/* CSS Document */
body{
color:#FFFFFF;
font-size:xx-large;
margin: 0;
padding: 0;
}
.twocolumn #header {
background-color:#00FF00;
padding: 10px;
height: 100px;
}
.twocolumn #left {
position: absolute;
background-color:#FF0000;
width: 200px;
height:400px;
}
.twocolumn #center {
background-color:#0000FF;
margin-left: 200px;
height:400px;
}
.twocolumn #footer{
background-color:#CC00CC;
}
Hope you can help me here, the only solution that I can find right now is changing the width to px or em which is quite difficult for me. Thank you.