Stalled until new profiles are live on beta in production and we've had a chance to review.
- Monitor for feedback on mobile web beta channel
- Ensure tests are passing
- Place on the train
- Check with @Nirzar what should happen with cached HTML. Options here include using JS to load the new UI ($$), flushing cache ($$$), loading css via JS but not making html changes ($), showing a warning that a user is viewing an old version and a link to action=purge to fix it ($), nothing (free)