Note 2 - Significant Accounting Policies - Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss per Share (Details) - shares |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Anti-dilutive securities not included in calculation of diluted net loss per share (in shares) | 4,002,834 | 6,506,465 | 3,952,473 | 6,629,488 |
| Share-Based Payment Arrangement, Option [Member] | ||||
| Anti-dilutive securities not included in calculation of diluted net loss per share (in shares) | 1,886,584 | 3,865,148 | 1,817,407 | 3,993,693 |
| Warrant [Member] | ||||
| Anti-dilutive securities not included in calculation of diluted net loss per share (in shares) | 2,116,250 | 2,116,250 | 2,116,250 | 2,116,250 |
| Unvested Restricted Stock Units [Member] | ||||
| Anti-dilutive securities not included in calculation of diluted net loss per share (in shares) | 0 | 525,067 | 18,816 | 519,545 |