Note 6 - Stockholders' Equity and Stock-based Compensation - Summary of Performance Option Activity (Details) - Performance Options [Member] - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Options balances, number of shares (in shares)	520,302
Options balances, weighted average exercise price (in dollars per share)	$ 10.08
Options balances, weighted average remaining life (Year)	8 years 6 months 10 days	7 years 7 days
Options granted, number of shares (in shares)	848,000
Options granted, weighted average exercise price (in dollars per share)	$ 3.13
Options exercised, number of shares (in shares)	0
Options exercised, weighted average exercise price (in dollars per share)	$ 0
Options canceled, number of shares (in shares)	(53,500)
Options canceled, weighted average exercise price (in dollars per share)	$ 2.31
Options expired, number of shares (in shares)	(90,672)
Options expired, weighted average exercise price (in dollars per share)	$ 11.35
Options balances, number of shares (in shares)	1,224,130	520,302
Options balances, weighted average exercise price (in dollars per share)	$ 5.51	$ 10.08
Options exercisable, number of shares (in shares)	443,628
Options exercisable, weighted average exercise price (in dollars per share)	$ 7.57
Options exercisable, weighted average remaining life (Year)	7 years 9 months