Hi Jennifer,
What a wonderful coincidence, we have just done the very same thing for one of our clients using the Minimal theme. They loved the theme yet yearned for a sidebar. So we'll be able to do this for you super quick, plus the ability to expand collections when sub-collections/menus are created in your navigation. We'll add a splash of colour too. Send a message to hello@bakecreative.co.uk to have a chat about this.
Many thanks
Dawn, Bake Creative