Note 5 - Shareholders' Equity - Reserved Shares (Details)	Mar. 31, 2022 shares
Shares reserved (in shares)	10,710,572
Series A Preferred Stock Warrants [Member]
Shares reserved (in shares)	128,572
Series A Preferred Stock [Member]
Shares reserved (in shares)	5,482,000
Series B Preferred Stock [Member]
Shares reserved (in shares)	1,700,000
Series C Preferred Stock [Member]
Shares reserved (in shares)	1,700,000
Series D Preferred Stock [Member]
Shares reserved (in shares)	1,700,000