Another small experiment - i built a full harness for building UI, i call them "gym" like old school RL environments. So i have a gym where model can measure rendered dimensions, also can screenshot components, also can calculate optical center and write unit tests with all calculations of dimensions and layouts. It seems it is working, but a simple square/circle avatar component costs north of 150k tokens of Fable 5. Which i guess is expected and right amount of tokens needed to vertically center text in both browsers.