Like the first chords of “Dancing Queen” and the blue lame fabric of the costumes, the faces on the Center for Theater Arts stage shimmered in last week’s performance of “Mamma Mia!” No Broadway cast could have radiated more fun.

Many of those performers were Mt. Lebanon High School students, including Grace Kearns (whose vocals as Donna Sheridan were especially lovely), Jacob Malizio (Sky), Maddie McCarthy (ensemble), Mira Morris (ensemble) and Olivia Cancelliere (ensemble).

The community feel of the event was evident as family members found each other in the auditorium, neighbors exchanged greetings and mothers raced up the aisles at intermission to staff the snack bar. The packed parking lot was testament to the crowd’s dedication to the actors and the center on a night with record-setting wind chills. (Shows later in the weekend had to be rapidly relocated from Upper St. Clair High School to Bethel Park High School after a water main break, further proof of the can-do attitude of this group).

Performers were joined by the clapping audience for an enthusiastic and spontaneous singalong as the show ended. Then the actors from the stage melted back into the hoodie-clad teens who parents and grandparents had driven to the venue. But the joy lingered on their faces.