A post-deployment, position-stabilized curtain airbag has a top edge from which an inflatable safety cushion is supported by a vehicle for deployment into a vehicle passenger compartment between occupant and occupant enclosure. A fill chamber is secured to the top edge of the safety cushion. An inflatable structural member is mechanically connected to the safety cushion. The fill chamber directs pressurized gas into the safety cushion and the structural member. The structural member deploys into the passenger compartment between the safety cushion and occupant enclosure limiting outboard displacement of the safety cushion. The structural member fully deploys after the safety cushion. Another structural member deploys along the top edge of the safety cushion limiting pivoting of the safety cushion there relative to the fill chamber. Pressurized gas enters each structural member through auxiliary passageways having oppositely directed entrances and outlets.