Oooh, nice work on the dynamic music! It's subtle, but very satisfying to hear in-game.
The puzzles are pretty fun as well too. I was afraid to be lost with my colorblindness (although I had zero issue identifying each color, so it was mostly my terrible memory when it comes to color blending), but since the goal of all level is to obtain white, with always the same three colors at the start, it was actually very easy to understand! And the level themselves are challenging, but manageable enough to be satisfying to solve! Actually the last levels might be a bit easier, since they are more linear. But their solution still feel elegant, especially the last one!
One major issue though: moving mirrors tiles by tile is very laborious. It takes a lot of time to place them as we want, and require repetitive inputs (space, move, back, space, left, move, back, etc). The area 10 thus felt a bit like a chore, as it consists mostly to move all mirrors from one end of the level to the other! I would have preferred to not think too much of the cost of moving mirror, to just dispose them quickly and try solutions.
Besides that, it's a great entry! Cool concept, neat art and music, tight level-design, and yet a generous number of levels, all interesting!