Div margin-bottom of a proportion of its own height?

Question

For example, I have a div that has a height of 100px (I don't know the height, but let's suppose I did). I want to set the margin-bottom to a percent, so 25% would be 25px assuming the previous height. However, the percent seems to be of the document, not the element:

<div style="height:100px;margin-bottom:100%"></div> 

The margin should be 100px but it isn't, it is 100% of the height of the page.

The element is just a line of text that has no background, so using height:150% theoretically could also work.

Answer 1

How about a CSS3 solution:

div {            -webkit-transform: translateY(-50%);    -moz-transform: translateY(-50%); }