Parse the Viewport from eg. a scroll event.

This is an Elm-only version of what Browser.Dom.getViewportOf does.

Map a Browser Document from one msg type to another.

type Msg
    = HomeMsg Home.Msg


view : Page -> Browser.Document Msg
view page =
    case page of
        Home model ->
            mapDocument HomeMsg (Home.view model)




-- Home.elm
view : Home.Model -> Browser.Document Home.Msg