I’m using the Vigilance theme with the Custom Design upgrade. I’d like to add a custom background image to visionofthecity.org (instead of the flat gold color fields). However, while the management options on my theme allow me to define the color of the fields on either side of the content, it doesn’t let me swap them out for an image. Is there a way to do this with CSS? If so, would it be better for me to create a small image that I tile, or can I create a larger one that remains static while the content scrolls past it?