centered page using css

html code
<div id="header">
</div>
<div id="wrapper">

</div>
<div id="footer">
</div>

and css file:
body
{
text-align: center;
background-color:#ffd79b;
min-width:760px;

}




#header
{
top:0px;
border:3px solid orange;
margin:0 auto;
width:1000px;
height:300px;
background-color:white;

}


#wrapper
{ width:1000px;


margin:0 auto;


text-align: left;
border:3px solid orange;
height:500px;
position:relative;
background-color:white;


}
#footer
{
margin:0 auto;
width:1000px;
margin-top:auto;
border:3px solid orange;
height:100px;
background-color:white;
}