Colored bars in lessons by browser version.
By untimed exercising in the browser version, you have a colored bar (green, blue or red), indicating how many sentences you have answered correct. What is the meaning of these colors?
They correspond to the colours the skills have on your home screen, which seem to be pretty random. There is not real meaning to them on the bars.
In an A/B test that's currently running the bar is green regardless of which skill you're working on.