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Note 10 - Share-based Compensation - Summary of Stock Option Valuation Assumptions (Details) - $ / shares
3 Months Ended 12 Months Ended
Mar. 31, 2022
Mar. 31, 2021
Dec. 31, 2021
Forfeiture rate 0.00% 0.00%  
Weighted-average fair value of options granted (in dollars per share) $ 1.72 $ 2.42  
Share-Based Payment Arrangement, Option [Member]      
Expected stock price volatility 49.00% 50.00%  
Risk-free interest rate 1.57% 0.89%  
Expected dividend yield 0.00% 0.00% 0.00%
Expected life of options (Year) 1 year 4 months 20 days 5 years 8 months 12 days