Responsive design rule adding CSS to back-end

I want to set up some responsive design rules in Sitefinity that will load a different CSS file for different devices: one for mobile phones, one for tablets, and one for desktops. I figured I could do this by creating a new rule for each one and selecting "Transform the layout" under the Apply behavior to... section, and selecting the appropriate file for each rule (see transform.png). The problem is that, contrary to what I'd expected, the CSS file is also being applied to the Sitefinity admin back-end as well as the front-end, which messes up the layout a fair bit (see messed up.png). I don't particularly want my CSS to be applied to the back-end; is there a way to get around this problem?