what caused the brief period of contentment for Liesel and papa Hubermann during the summer of 1942

I think this is when Hans gets a little work painting people's window blinds black.

Liesel goes with him on the jobs. She watches him mix paint. For a little while things are reletively pleasant.One day, when they are painting at a wealthy home, Hans and Liesel are invited to the kitchen and Liesel has her first taste of champagne.