I was wondering if there is a way to show different layouts of the same MM to different users?

My example is that I will have a permanent MM set up, but will also view the content on a phone, TV, and laptop, and I would like it to have formatting correct for each one. I am using MM as a dashboard, kind of like the old iGoogle homepage.

Is there a way to do this via CSS by differentiating user-agents/browsers, or could I run multiple different MMs and then bookmark them individually on each device.