Div Centered Vertically and Horizontally

<.div id="horizon">
<.div id="content">




Css :

#horizon {
background-color: transparent;
color: white;
display: block;
height: 1px;
left: 0;
overflow: visible;
position: absolute;
text-align: center;
top: 50%;
visibility: visible;
width: 100%;
}
#content {
background-color: transparent;
font-family: Verdana,Geneva,Arial,sans-serif;
height: 70px;
left: 50%;
margin-left: -125px;
position: absolute;
top: -35px;
visibility: visible;
width: 250px;
}