Note 6 - Common Stock Options - Changes in Common Stock Options Issued (Details) - $ / shares	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025
Options outstanding (in shares)	5,473,907	4,331,585
Granted (in shares)	11,800	1,066,096
Exercised (in shares)	0	0
Exercised, exercise price (in dollars per share)	$ 0	$ 0
Forfeitures (in shares)	(104,750)	(45,000)
Options outstanding (in shares)	5,380,957	5,352,681
Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 2.31	$ 2.71
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	2.31	3.25
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	3.84	3.84
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	2.31	2.71
Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	21.74	21.74
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	2.61	3.89
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	16.5	19
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	21.74	21.74
Weighted Average [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	7.45	8.89
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	2.45	3.52
Exercised, exercise price (in dollars per share)	0	0
Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Forfeitures in Period, Weighted Average Exercise Price	9.23	12.44
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 7.41	$ 7.8

The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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Number of options outstanding, including both vested and non-vested options.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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