Ant-design: Affix demo doesn't work properly

Version

2.9.0

Environment

Chrome 56, Firefox 47

Reproduction link

https://ant.design/components/affix/

Steps to reproduce

1. Mouse over the "Container to scroll" demo
2. Scroll down inside the container.
3. Continue scrolling down after container reaches it's bottom causing the browser window to scroll down

Firefox does not automatically scroll the entire page when reaching the bottom of the container, but moving the mouse outside of the container and continuing to scroll down produces the same issue.

Additionally, the affixed component does not reposition itself on browser window resize. It will not move itself into the container until the container is visible again.

What is expected?

Affixed component should remain inside the container and scroll with the browser window

What is actually happening?

Affixed component stays affixed to the same position within the browser window