Gap is not huge, about 2mm at its worst, but it's irritating me the hell out of me; not an even gap all the way around and is pretty obvious due to it being white against white. I have tried adjusting every which way but it's a combination of the ceiling very slightly out and the chimney. The fixings are pretty rubbish. If the chimney was slightly more robust I would put a small bead of silicone but not sure that would stay in place. I am thinking a plastic U channel strip over the edge...
Cooker Hood - slight gap between chimney top edge and ceiling
Cooker Hood - slight gap between chimney top edge and ceiling