Add margin to header row to fix scrolling issue

[baymac]

Scroll bar in windows takes up space so that table is distorted when there is a fixed header. E.g. see below screenshot:

It can be fixed by adding a margin right that is the width of the scrollbar to the header row. The header row should only have a margin right but not the rows. I am unable to do it.

Here is a codesandbox https://codesandbox.io/s/blissful-edison-p6gch?file=/src/App.js.

This is from virtualized row example. I have added some scrollbar styles then I am trying to add a margin right to header div but it is also applying to the rows div.