Since the past day or two, the mobile editions SU/MSU are being shown without the stylesheet.
This happens on Android stock browser as well as Dolphin HD. Clearing cache has made no difference
I configured the CDN incorrectly in one spot. I'm not entirely sure how or why this caused this issue – my theory at the moment is that the Android browser and the CDN outsmarted each other with regards to caching – but either way it should be fixed now.
I just cleared my cache and refreshed: problem solved!