What is the reason for the special treatment of fixed-* and sticky-* elements when the scrollbar disappears during modal.show?

[tesar-tech]

When using a modal, the scrollbar is removed from the body, and padding is added to compensate for the scrollbar width, ensuring the layout remains consistent. This functionality is handled by Bootstrap's scrollbar.js.

However, there is also special treatment for elements with sticky or fixed classes. I’m trying to understand why this is necessary, as everything seems properly aligned with just the padding on the body.

I can’t identify a layout scenario where this special treatment would be required to prevent alignment issues.

Thank you.