Note 7 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	3 Months Ended	6 Months Ended		12 Months Ended
	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Outstanding, balance (in shares)	95,000	146,000	95,000	95,000
Balance, grant date weighted-average exercise price (in dollars per share)	$ 2.76	$ 2.83	$ 2.76	$ 2.76
Balance, weighted average remaining contractual life (Year)		2 years 9 months 21 days	5 years 9 months 3 days	5 years 5 months 8 days	4 years 9 months 29 days
Balance, aggregate intrinsic value		$ 28,000		$ 0	$ 25,000
Forfeited (in shares)		(84,000)	(19,000)
Forfeited, grant date weighted-average exercise price (in dollars per share)		$ 2.87	$ 2.69
Outstanding, balance (in shares)		62,000	146,000	146,000	95,000
Balance, grant date weighted-average exercise price (in dollars per share)		$ 2.76	$ 2.8	$ 2.83	$ 2.76
Exercisable (in shares)	20,000	42,000
Exercisable, grant date weighted-average exercise price (in dollars per share)	$ 2.92	$ 2.76
Exercisable, weighted average remaining contractual life (Year)	2 years 8 months 1 day
Granted (in shares)			70,000
Granted, grant date weighted-average exercise price (in dollars per share)			$ 2.82
Granted, weighted average remaining contractual life (Year)			7 years
Minimum [Member]
Exercisable, weighted average remaining contractual life (Year)		1 year 6 months 25 days