IT was early August, and clouds of tear gas drifted through much of Athens, the remnants of protests against austerity measures. But the country’s financial woes seemed far from the minds of the smartly disheveled young Greeks packed onto the roof terrace of the newly opened Fragile bar in Salonika, about 320 miles north of the capital. T-shirt-clad art students shouted over a mix of vintage doo-wop and ’90s alt-rock, or ducked into the covered bar area, which evoked a vaguely postal theme, its corkboard-lined walls cross-hatched with packing tape.