Summary of significant accounting policies - Revenues - Disaggregation by Product Line (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Disaggregation of Revenue [Line Items]
Total	$ 30,501,460	$ 33,212,548
Sanitaryware
Disaggregation of Revenue [Line Items]
Total	16,126,369	20,159,852
Bath Furniture
Disaggregation of Revenue [Line Items]
Total	4,546,147	4,100,382
Shower System
Disaggregation of Revenue [Line Items]
Total	6,480,302	5,686,317
Others
Disaggregation of Revenue [Line Items]
Total	$ 3,348,642	$ 3,265,997