In brief
counter-reset creates a named CSS counter and sets its initial value. Other rules can then increment and display it on headings or items.
Useful to know
counter-reset creates a named CSS counter and sets its initial value. Other rules can then increment and display it on headings or items. [1]
Placement matters: a counter created in every section can start again there. If numbering restarts unexpectedly, inspect the rule's scope rather than only its increment value.
Sources
For further detail and to check the information: