10% penalty on the interest, no penalty on the principal. Some states may assess their own, California adds 2.5% for a whopping 12.5% total. Your broker should have some info about the principal (basis) and by most accounting practices it would be considered FIFO so if you take an amount up to the principal it won’t be counted as a penalty.
Your stock losses are irrelevant as far as the Roth withdrawal is concerned. If it was 100% interest withdrawal, you’d pay a penalty of $350 not $0.