The top of Salesforce Tower is illuminated with artist Jim Campbell’s contribution in support of medical workers and first responders fighting Covid-19 with video of clapping hands and prayer flags. The artist’s “Day for Night,” video show atop the tower, changed at 7 p.m. on Wednesday, with clapping hands taking it’s place, then changed at 8:30 p.m. to prayer flags until 12:30 a.m.