are you trying to center the div both horizontally and vertically? Is this div the only thing on the page or is it a child of another div?
The easy way would be to contain the div inside a table. i know I know...tables bad, but tables work for this.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
<title>centered divs</title>
<style type="text/css">
table {
width: 100%;
height: 100%;
}
td {
vertical-align: middle;
text-align: center;
}
#box {
width: 200px;
height: 200px;
background-color: #fc6;
margin: auto;
}
</style>
</head>
<body>
<table><tr><td><div id="box"></div></td></tr></table>
</body>
</html>
pretty sure DocType is essential.
as a child:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
<title>centered divs</title>
<style type="text/css">
body {
text-align: center;
}
table {
width: 100%;
height: 100%;
}
td {
vertical-align: middle;
text-align: center;
}
#box {
width: 200px;
height: 200px;
background-color: #fc6;
margin: auto;
}
#container {
width: 600px;
height: 600px;
margin: 0 auto;
border: 1px solid #000;
}
</style>
</head>
<body>
<div id="container">
<table><tr><td><div id="box"></div></td></tr></table>
</div>
</body>
</html>
in columns with a slight fudge to appese IE:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=iso-8859-1">
<title>centered divs</title>
<style type="text/css">
body {
text-align: center;
}
table {
width: 448px;
height: 100%;
float: left;
}
td {
vertical-align: middle;
text-align: center;
}
#box {
width: 200px;
height: 200px;
background-color: #fc6;
margin: auto;
}
#container {
width: 600px;
height: 600px;
margin: 0 auto;
border: 1px solid #000;
}
#left {
width: 150px;
height: 600px;
background-color: #63c;
float: left;
}
</style>
</head>
<body>
<div id="container">
<div id="left"></div>
<table><tr><td><div id="box"></div></td></tr></table>
</div>
</body>
</html>
you can accomplish this with negative margins but this just seems easy enough to do to not worry about the negative margins getting chewed up by old browsers.
