How can I center a logo image in an Omega theme? I'm using Omega (a subtheme obviously) and am having trouble centering my logo image. I tried adding a .logo-img CSS class to my global.css file but it isn't doing anything. I added the following, but results are weird:

margin-left: auto;
margin-right: auto;
border: 4px solid;


I added the border to see the image field because when I save these settings, the image stays on the left, but the border extends all the way to the right.

So those settings end up in the logo image resulting like this: http://i.imgur.com/1r8Bccc.jpg?1 (sorry I can't post images)

If I comment out the margin lines in the css file, the image stays the same.

I honestly don't know how to fix this. Is there a way to do this within my theme's settings? I can't find anything online or in the documentation.
By default the Omega theme CSS floats the image within branding left. You'll have to set it to float none.