Fixing image to container size in Grid layout

hey guys, I have been trying out the grids layout and was wondering how I get the images for the posts to fit the containers as we did in magazine layout. I have tried the following code in my custom CSS but it's obviously not right.

body #eb .eb-blog-grid-image {
background-size: contain !important;
background-position: center !important;
}

I have disabled the showcase option in the wireframe so using an over ride. and I have now used the easyblog showcase module to replace this and have the same image size issue here - I have it set up as magazine option here, is it possible to get this to size to the container?