I’m posting this because occasionally I forget.. it’s by far the easiest method that works across all major browsers!
body {
margin:50px 0px; padding:0px;
text-align:center;
}
#Content {
width:500px;
margin:0px auto;
text-align:left;
padding:15px;
border:1px dashed #333;
background-color:#eee;
}