Table bottom positioning via css - firefox and opera wont do it

hi

i’m trying to create a resizeable background with a number of tables and images, and the way i want to do it is by external css.

while this works fine in ie, firefox (and opera, for that matter) seems to take a liking in disregarding my css values concerning the height of the main table holding the background images.

the css-code:
.main {
valign: middle;
width: 100%;
height: 100%;
}
the table ini:
<table border=“0” cellpadding=“0” cellspacing=“0” class=“main”>

in detail: i have 3 images that have to be at the bottom of the browser-window.

  1. the left bottom corner, 2. the right bottom corner and 3. the “bridge” between the two corner pics.

i have it working for the top, because top-alignment seems to be no problem for firefox and opera…

is there some way to work around this behaviour? even it it aint css. i just want this thing working properly…

thx in advance for any solutions or clues!