Fix: content is pushed due to scroll bar

[JoeyC-Dev]

If you switch pages between long and short pages, you will find out the the align is different.

Solution: https://developer.mozilla.org/en-US/docs/Web/CSS/scrollbar-gutter#example_1

Tried auto-hide scroll bar but cannot solve the issue: still pushing the content.

This property is not supported on Safari, but still better than using "hiding scroll bar" as solution. I cannot find other way to fix the issue.