The "Zero Line" is the calculated logarithmic regression of Bitcoin over the last decade.
The rainbow above the Zero Line are the Fibonacci multiples from 0 --> 1 of the log regression (0.236, 0.382, etc.)
The rainbow below the Zero Line is identical, except that the multiples are negative (-0.236, -0.382, etc.)
For the first time ever, Bitcoin broke through the Zero Line (the natural regression) when it dumped on March 12-13. It looked at though the regression was invalidated when, in fact, it simply made an unprecedented move to a lower Fibonacci multiple.
Enjoy.