Is it permissible to work for a company that carries out advertising work for casinos and bars, given that the designer himself refuses to do such work, and is his salary considered unlawful, and does the need for employment make it permissible to undertake such work?

It is impermissible to advertise for evil deeds due to the cooperation in sin involved therein. If it is possible to refrain from advertising for evil deeds and to restrict oneself to permissible matters, then there is no harm in continuing, with the priority of seeking another job. As for the need that permits advertising for evil deeds, it is one that reaches the level of necessity, such as a person not finding what suffices their basic needs of food, drink, and clothing, to the extent that they or their dependents are on the verge of perishing, based on the Almighty’s saying: "And He has already explained to you what He has forbidden to you, except for that to which you are compelled." One should remain in this work only until the necessity ceases, and they must strive to find another job.