s.a arkadaşlar footer ya sayfanın ortasında oluyor yada aşağı kaymıyor sabit en altta duruyor sayfa aşağı indikçe footer ın altında kalıyor.bu sorunu nasıl düzeltirim.. yardımcı olursanız sevinirim.

#ana{ 
width:100%; 
height:326px; 
margin: 0;  
padding: 0; 
position:absolute; 
} 
#ust{ 
width:100%; 
height:26px; 
background-image:url(images/ust.jpg); 
background-repeat:repeat-x; 
} 
#ust_alt{ 
width:100%; 
height:152px; 
background-image:url(images/ust_alt.jpg); 
background-repeat:repeat-x; 
position:absolute; 
} 
#alt{ 
width:100%; 
height:117px; 
background-image:url(images/alt.jpg); 
background-repeat:repeat-x; 
bottom:0px; 
text-align:center; 
margin-left: auto; 
margin-right: auto; 
position:absolute; 
} 
#orta_ust{ 
width:700px; 
height:46px; 
background-image:url(images/orta_ust.png); 
background-repeat:no-repeat; 
margin-left: auto; 
margin-right: auto; 
margin-top: 130px; 
margin-bottom: auto; 
position:relative; 
float:center; 
} 
#orta_alt{ 
width:700px; 
height:22px; 
background-image:url(images/orta_alt.png); 
background-repeat:no-repeat; 
margin-left: auto; 
margin-right: auto; 
} 
#buton{ 
width:700px; 
height:35px; 
background-image:url(images/buton_alt.png); 
background-repeat:no-repeat; 
margin-left: 8px; 
margin-top: 8px; 
position:absolute; 
} 
#orta_orta{ 
width:700px; 
background-color:#ffffff; 
margin-left: auto; 
margin-right: auto; 
padding-left: 10px; 
padding-right: 10px; 
} 
#alt_yazi{ 
width:500px; 
height:70px; 
background-color:#ffffff; 
margin-top:30px; 
padding:3px; 
} 
#a{ 
margin-left: auto; 
margin-right: auto; 
width:688px; 
height:174px; 
background-image:url(images/a.png); 
background-repeat:no-repeat; 
} 
#b{ 
margin-left: auto; 
margin-right: auto; 
width:688px; 
height:174px; 
background-image:url(images/a.png); 
background-repeat:no-repeat; 
}
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 

<head> 
<meta http-equiv="Content-Language" content="tr"> 
<meta http-equiv="Content-Type" content="text/html; charset=windows-1254"> 
<link rel="stylesheet" href="css.css" type="text/css" /> 
</head> 
<body topmargin="0" leftmargin="0" rightmargin="0" bottommargin="0"> 
<div id="anaa"> 
<div id="ana"> 

<div id="ust"></div> 
<div id="ust_alt"> 
<div id="orta_ust"> 
<div id="buton">asdasd</div> 
</div> 
<div id="a">zdasd</div> 
<div id="b">zdasd</div> 
<div id="b">zdasd</div> 
<div id="b">zdasd</div> 
<div id="b">zdasd</div> 
</div> 
</div> 

<div style="clear:both;" ></div> 
<div id="alt"> 
<div id="orta_alt"></div> 
</div> 

</body> 
</html>