Note 8 - Preferred Stock and Common Stock Warrants - Fair Value Assumptions (Details)	Jun. 30, 2021	Dec. 31, 2020
Measurement Input, Share Price [Member]
Warrant measurement input	4.13	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	0.584	0.586
Measurement Input, Expected Term [Member]
Warrant measurement input	0.9	0.8