Make the story list scrolling snappy on iPad

Using (only) `overflow:scroll` apparently makes the scrolling sluggish. This will make it snappy again.

Possibly relevant reference: http://cantina.co/2012/03/06/ios-5-native-scrolling-grins-and-gothcas/

The following might need to be added, but I think let's see how it goes first (?)

    #story-list > * {
      -webkit-transform: translate3d(0,0,0);
    }

Reference: http://stackoverflow.com/a/11361719/252384