Aligning nav container with header image

Hello,

I'm using Counterform and trying to align the bottom of my right aligned nav links with the bottom of my header image. However, I can't seem to get this to happen.

I would also like for the nav container to remain right aligned, flush with the right edge of the thumbnails, as the browser window is resized just as the header image does (except flush left). Currently it seems to stay in a fixed position regardless of the window size but position is set to fixed.

My code looks like this:

.header_img {
clear: both;
margin: 0 auto 0 auto;
padding: 20px 0 0 35px;
position: relative;
width: 940px;
z-index: 10;
}

.nav_container.horizontal {
margin: 0px auto 0px 920px;
padding: 0px 0px 0px 0px;
position: relative;
width: 219px;
z-index: 10;
float:left;
}