Build web table with collapsible rows based on a csv file source

The table show show the main categories by default and then if user clicks then they will see the sub-categories.
This is the sort of thing i want : https://stats.centr.org/classifications#C1 however i think it could look nicer. for example, i think the one at https://getbootstrap.com/docs/4.0/components/collapse/ might be good.

the data at https://stats.centr.org/classifications#C1 is actually the exact data i need too. click the 'simple' download to view the actual data.