Background overflows outside of bounds

[nick-merrill]

Notice the tiny sliver of image on the right side of this background image. It comes from the "Settings" tab, which has another parallax view in it. It's flowing into my other content (because it's pre-rendered), but I don't want it to.

A simple fix is to apply an overflow: "hidden" style to the entire parallax view.

Happy to submit a pull request, but I want to make sure you think it's a problem worth fixing in Parallax View and not in my tab presenter. I did try preventing the overflow from my tab presenter, but I was unable to contain the overflow that way.