Note 7 - Stock-based Compensation - Summary of Stock Option Activity (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Outstanding, balance (in shares)	146,000	95,000	95,000
Balance, grant date weighted-average exercise price (in dollars per share)	$ 2.83	$ 2.76	$ 2.76
Balance, weighted average remaining contractual life (Year)	5 years 2 months 8 days	4 years 9 months 3 days	5 years 5 months 8 days	4 years 9 months 29 days
Balance, aggregate intrinsic value	$ 5,000	$ 26,000	$ 0	$ 25,000
Outstanding, balance (in shares)	146,000	143,000	146,000	95,000
Balance, grant date weighted-average exercise price (in dollars per share)	$ 2.83	$ 2.8	$ 2.83	$ 2.76
Exercisable (in shares)	42,000	48,000
Exercisable, grant date weighted-average exercise price (in dollars per share)	$ 2.86	$ 2.73
Exercisable, weighted average remaining contractual life (Year)		2 years 6 months 3 days
Granted (in shares)		50,000
Granted, grant date weighted-average exercise price (in dollars per share)		$ 2.93
Granted, weighted average remaining contractual life (Year)		7 years
Forfeited (in shares)		(2,000)
Forfeited, grant date weighted-average exercise price (in dollars per share)		$ 3.9
Minimum [Member]
Exercisable, weighted average remaining contractual life (Year)	3 years 10 months 2 days