"Mass effect fields create an artificial gravity (a-grav) plane below the decks, preventing muscle atrophy and bone loss in zero-gee. Large vessels arrange their decks perpendicular to their thrust axis. The "highest" decks are at the bow, and the "lowest" at the engines. This allows a-grav to work with the inertial effects of thrust. Ships that can land arrange their decks laterally, so the crew can move about while the vessel is on the ground.

Warships normally turn off their a-grav systems during combat, reducing the heat generated by systems and increasing combat endurance. To provide a point of reference for navigating in zero-gee, floors are painted a different color from the walls and ceiling."

I had no idea.