Detecting Screen Size and Mobile strategies

I didn't find these really in searching, so... 

(right now, we can't use the Articulate app) Is there a way for Storyline to detect the size of the screen it is playing on?  Meaning, if someone looks at a course on a tablet or laptop, the course should play the "full size" course, but if they are playing the course on a 5" or 5.5" phone screen it can automatically just use the mobile version of the course?

Right now, my solution is to just start the courses with a screen asking which version they want to take. Which leads me to the second part of this question:

We're looking at some mobile ideas, and I was thinking, instead of having our LMS tag the mobile courses as separate, and the learner has to basically guess at the LMS level, we could build both versions of the course in one story (two scene paths), and that opening slide to choose (or an automatic detector) would just channel the learner to the right version. The only real downside I see is size of the files. Is there a better way?