The birthday girl — whose big day was on Saturday — and her friends slept in Hello Kitty-themed tents decorated with blue, pink and purple balloons ... flowers, gold and pink chairs, stuffed ...

Sophia’s birthday backdrop was made up of purple, pink, and gold balloons, and she also had a baby blue and pink birthday ...

That will unleash a flurry of purple balloons that you can pop with a click or tap; clicking on the balloons with microphones will reveal special audio messages from the band members themselves.

By Billboard Staff Happy birthday ... desktop to unlock a special purple heart icon that appears on the left-hand side. Click on it to reveal a stream of purple balloons that you can pop by ...