Note 9 - Stockholders' Equity - Assumptions of Options (Details) - Share-Based Payment Arrangement, Option [Member] - The 2019 Plan [Member] |
6 Months Ended | |
|---|---|---|
Jun. 30, 2026 |
Jun. 30, 2025 |
|
| Expected dividend yield | 0.00% | 0.00% |
| Minimum [Member] | ||
| Expected life (years) (Year) | 5 years 9 months 29 days | 5 years 3 months 25 days |
| Expected stock-price volatility | 82.90% | 86.00% |
| Risk-free interest rate | 3.88% | 4.14% |
| Maximum [Member] | ||
| Expected life (years) (Year) | 6 years 3 months | 6 years 9 months 25 days |
| Expected stock-price volatility | 84.80% | 88.00% |
| Risk-free interest rate | 4.35% | 4.38% |