Questions & Answers about Qualunque sia la regola, non devi infrangerla.
Why is sia used here instead of the normal present tense è?
Words like qualunque (whatever) introduce a clause that shows uncertainty or a "no matter what" scenario. In Italian, this requires the subjunctive mood, which is why we use the subjunctive sia instead of the indicative è.
Why is the subject la regola at the end of the first clause?
When starting a clause with an indefinite word like qualunque or chiunque plus the subjunctive, Italian strongly prefers inverting the subject and the verb. Saying Qualunque la regola sia would sound unnatural.
What does the la at the end of infrangerla mean?
Why is infrangere in its infinitive (dictionary) form here?
Because it follows devi, a conjugated form of the modal verb dovere (must). Whenever you use a modal verb, the main action verb that follows it must stay in the infinitive.