How do I position a div at the bottom center of the screen

Question

I have this css:

#manipulate
{
  position:absolute;
  width:300px;
  height:300px;
  background:#063;
  bottom:0px;
  right:25%;
}

I have t

Answer 1

Use negative margins:

#manipulate
{
  position:absolute;
  width:300px;
  height:300px;
  margin-left:-150px;
  background:#063;
  bottom:0px;
  left:50%;
}

The key here is the width, left and margin-left properties.