Note 5 - Prepayments and Deposit to Suppliers (Details Textual) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2021 USD ($)
Cryptocurrency Mining Machine Purchase [Member]
Purchase Agreement Prepayment		$ 1.5
Purchase Agreement, Expected Refund	$ 1.5
Potential Merger and Acquisition [Member]
Business Combination, Nonrefundable Deposit	$ 1.0	$ 1.0