In 2011, Apple released Mac OS X Lion which introduced an enhanced scrollbar behavior that made scrollbars hidden by default. This enhancement did not only change the user interface, but has also shaped how developers (don't) think about that specific UI element when creating cross-platform solutions. I call it scrollbar blindness.
As your React application grows bigger, it's time to think about cutting the bundle into smaller pieces, so that the users of your website could enjoy a better experience. This article explains how to do just that in ReasonML with ReasonReact.