For fun I added a couple extra visual modes that I can cycle through with the pushbutton. People seemed to like the red-blue combo the most. If you can catch it in the video, the different colors cycle at different speeds.
You can solder a small tactile button directly to the Trinket from 3V (or 5V) to Pin 1 and the LED circuit will act as a pull down. Helpful for reducing wiring in a simple and quick project like this one. Inspiration from here (see bullet 2): https://learn.adafruit.com/tap-tempo-trinket/things-learned