As the title says, a mod undeleting a comment adds a second top bar, adds a random second copy of the logo and top buttons in the middle of the page, pushes the comments to the bottom of the page, and adds some other graphical issues.
This occurs on both scifi and outdoors.
A picture says a thousand words:
Chrome 61.0.3163.100 (Official Build) (64-bit)
macOS Sierra/10.12.6