embed a footer at the bottom of a div

How do i embed

<div id="site-wrapper">
   <div id="footer"></div>
</div>

to appear at the bottom of the div always .

#footer{
开发者_开发技巧 position:relative;
 height: auto;
 margin-bottom: 0px;
}

You need:

#site-wrapper {
  position: relative;
}

#footer {
  position: absolute;
  bottom: 0px;
}

#footer { 
position: absolute; 
bottom: 0px; 
}

Should work.