Intro page for mobile devices

[Jonas VanBommels]

I created a website using refinery. The site has two different layouts, one for mobile devices and a normal layout (I had to do this because the customer wanted me to).
Therefore I’ve overwritten the pages controller and put a mobile switch into the render_with_templates method. I also removed the template switch from the advanced options in the page view of the admin panel.

Now i have to create a intro page which appears for some seconds, but only on mobile devices. There will still be a normal "home"-page, the intro page should only appear if I call the URL without any arguments.
I have no idea how to do this, I hope you can help me with this, thanks!