Note 8 - Preferred Stock and Common Stock Warrants - Fair Value Assumptions (Details)	Mar. 31, 2021	Dec. 31, 2020
Measurement Input, Share Price [Member]
Warrant measurement input	2.67	2.09
Measurement Input, Exercise Price [Member]
Warrant measurement input	0.01	0.01
Measurement Input, Risk Free Interest Rate [Member]
Warrant measurement input	0.001	0.001
Measurement Input, Price Volatility [Member]
Warrant measurement input	0.358	0.586
Measurement Input, Expected Term [Member]
Warrant measurement input	1.0	0.8