"Even though it was my birthday...": "Bien que c'était mon anniversaire" doesn't fit in this construction. We could say "Bien que ce fût mon anniversaire..." Sérane
Hello Sérane, thanks for your comment! We try to avoid using the past subjunctive in our lessons, because it's so rare these days and never used in spoken French! But we have now changed this translation, from "c'était" to "ç'ait été".
Have a nice day!