Summary of significant accounting policies (Details)	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Period End [Member] | China, Yuan Renminbi
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.2265	7.10700	6.8689
Period End [Member] | Hong Kong, Dollars
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.8255	7.81005	7.85
Average [Member] | China, Yuan Renminbi
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.1511		6.8423
Average [Member] | Hong Kong, Dollars
Intercompany Foreign Currency Balance [Line Items]
Exchange rate	7.8202		7.8392