Minimalistic but perfect custom scrollbar plugin  Demo

perfect means...

• There should be no css change on any original element.
• The scrollbar should not affect the original design layout.
• The design of the scrollbar should be (nearly) fully customizable.
• If the size of the container or the content changes, the scrollbar size and position should be able to change.
• New! It should work with vanilla JavaScript and major tools like NPM or Browserify.