Can't figure out how to center the nav bar in amsterdam layout?

Hi!

I've finally figured out how to center my header, but can't seem to get my navigation to be centered as well.

cargocollective.com/rachelanneorr
As you can see, its just kind of there, I just want it to be centered!

My css looks like this:

.nav_container {
position: relative;
text-align: center;
margin: 0px auto;
bottom: 5px;
}

.nav_container div {
float: left;
margin: 0 0 0 24px;
}

.nav_container br {
display: none !important;
}

Any input would be super super helpful! I'm getting frustrated! Please Help :)

Thanks!

Rachel