Layers transition correctly

This time it handles scrolling. No need for scroll top.


![layers-with-scroll](https://cloud.githubusercontent.com/assets/814861/5318024/588c795a-7c94-11e4-955d-e726e5096061.gif)

Should the title here be amended as follows to make sense when there hasn't been any content to begin with?

```
"Sorry, there was an error fetching " + (!!this.prerender.template ? "the rest of" : "") + " this content."
```

... or something like that at least?