Scrolling should dismiss image or be locked

**Current behaviour** - based on the CodePen example:
Opening a gallery does not stop scrolling. The user can dismiss the image via touch (or dragging).

**Desired behaviour:**
a.) Scrolling would dismiss the image, similiar to https://github.com/francoischalifour/medium-zoom
b.) Scrolling would be locked if a Parvus lightbox is open