Note 8 - Stock-based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Beginning balance, unvested restricted stock units, shares (in shares)	45,003	100,005
Beginning balance, unvested restricted stock units, weighted average grant date fair value (in dollars per share)	$ 1.51	$ 1.50
Forfeited, restricted stock units, shares (in shares)	(40,000)	(5,000)
Forfeited, restricted stock units, weighted average grant date fair value (in dollars per share)	$ 1.32	$ 0.97
Vested, restricted stock units, shares (in shares)	(45,003)	(50,002)
Vested, restricted stock units, weighted average grant date fair value (in dollars per share)	$ 1.51	$ 1.50
Granted, unvested restricted stock units, shares (in shares)	807,048
Granted, unvested restricted stock units, weighted average grant date fair value (in dollars per share)	$ 1.32
Ending balance, unvested restricted stock units, shares (in shares)	767,048	45,003
Ending balance, unvested restricted stock units, weighted average grant date fair value (in dollars per share)	$ 1.32	$ 1.51