index.html.in: more work on the QR focus

index.html.in: more work on the QR focus

Tapping the QR code now brings it into focus and centers it in the
ticket, accompanied by a nice CSS transition that mimics the real
thing. The timing was adjusted to make the transition faster, and a
portability issue was hacked around. What does work, works in both
Firefox and WebKit (on the desktop) at least.

Still to-do is the ticket resizing that takes place when the QR code
gets bigger, and the vertical translation of the (growing) QR code.