That comes from the bootstrap based theme/template. I've been working on cleaning up some of the pages using panels and sections -- they all come from this enhancment:
DokuWiki Bootsrap WrapperIt's going to take a little time to get everything sorted back properly but definitely mention something if you see it!
EDIT:
Have corrected the vehicle page with panels -- this is ultimately how all of our pages should be updated.
As for the Table of Contents, I've adjusted it so that it will no longer auto-collapse on scroll. This gives the user the option to collapse it on their own. It'll also stay attached to the top of the window as the user scrolls so they can see what section they're in. Let me know if this is bothersome -- that can be configured as well.