Horizontal center dynamic image in div with absolute position

Question

I have looked all over the web for this answer but it seems to me that in order to horizontally center an image in div with absolute position, I need to know the dimensions of the image, but it's dynamic.

Here is my html:

<header>
<div id="elogo">
    <img src="http://www.ftiweb.com/images/eStore/eStore_wht50.png">
</div>
<div id="nav">TOUR | MENU</div>
</header>
<div id="content">
<img class="ipad" src="http://ftiweb.com/images/eStore/Ipad_hand.png">
</div>
<footer>
<div id="foot">&#169; FTIeStore 2013 &bull; Privacy Policy</div>
</footer>

and here is the .css I'm using:

#content {
width: 70%;
height: 80%;
border: 1px solid red;
position: absolute;
bottom: 0px;
left: 50%;
margin-left: -35%;
display: table-cell;

img.ipad {
max-width: 100%;
max-height: 100%;
position: absolute;
bottom: 0px;
display: block;
}

The goal is just to have the image stay at the bottom/center of the page and re-size to fit the browser window. If I'm over-complicating this, please feel free to suggest an alternative.

Here is a link to a js.fiddle:

bottom-centered img - js.fiddle

Answer 1

If you want it to be absolute position do it like this:

http://jsbin.com/aveped/1/edit

img {
  width:20%;
  display:block;
  position:absolute;
  left:0;
  right:0;
  bottom:0;
  margin:auto;
}

The parent needs to have position relative, or it will be positioned against the body. You dont need width for this, I just included width because my image is so big.

Answer 2

left = center position - half the width of the image

img {
   position: absolute;
   bottom: 0;
   left: 50%; /*half the container width*/
   margin-left: -250px; /*half the width of the image*/
}