Decorative Light with simple features

A small ATTiny project that implements a decorative light. It features three plain colors and a rainbow effect. The brightness of each light can also be controled within certain limits.
The project is an adaptation for ATTiny uC of similar projects created for Arduino UNO.
More info can be found: https://github.com/gkapsid/HomeProjects/tree/main/FirstATTiny (where the Decorative light is mentioned).

Tinkercad simulation: https://www.tinkercad.com/things/11Gc88x2S0x