I originally read this book between 2000 and 2006 and it was either in the teen or young adult section of the library and the things I remember are:
- The main characters are a girl and boy (romance subplot). I think she was from the present and he was from the future.
- She travels forward in time with him (could be accidental) and my main memory is that using his time travel device is partially done by moving your hands in a mobius strip pattern. They also may see an actual rainbow mobius strip when they do this.
- His father (some sort of military person in charge) does not like/trust her so she is locked up and will be sent back(?)
- The future world did not seem large as it mainly focused on the girl, the boy, his father and the immediate colony (?) in the area.
- She might have some sort of special ability to use their devices
- They use some sort flyer to travel around. Reminded me of a helicopter.
- Paradox: There is a scene where she and the boy are hiding in the bushes and waiting for and watching her past self escape for the tin shelter(?) where she is imprisoned.
- The book had a bright rainbow coloured softcover.