Differentiate letters with last speed above threshould with a different color (e.g. light blue)

[Dev2150]

When you're learning a new letter, you might do worse with other letters (because you need to make more connections).

I believe it would be better to see easier which letters still have a last speed above the desired threshould and otherwise, they will have the default color pick, from the gradient of green.

[Cosmatevs]

I'd even replace the current green with yellow, so the scale below the threshold would go from red to yellow, and the letters above the threshold would just be green.