On OEM 18s it might look ok on with the Sport ride height; the S-Line is only around 10mm lower. But if you fit aftermarket allows, they tend to be wider and lower offset which exposes rideheight issues a lot more.
Then there's the minfield of lowering the car, for some reason the A3 is a faff to lower, some springs just don't alter the ride height, andothers alter just the front and not the back. H&R -30mm for example raised the rear on my Sport??? The front looks perfect though, subtle lower but not obviously lowered.