Update:
The issues is caused by long string in project description https://connect.topcoder-dev.com/projects/2788. This is not a real world text sample so it is an edge case. We need to extend the CSS coverage of the sidebar to deal with very long words as this is what causes sidebar to come out of alignment and jump around when scrolling.
After the IE11 fixes the sidebar is jumping during scroll, and that's very apparent at narrow window size.

