What is the ruling on concealing the problem of baldness using kohl when applying for a job, and would the salary obtained from it be suspicious? And would the marriage contract be invalid if the suitor was not informed about the reality of thinning hair, or if she was informed but did not see the hair of the head before marriage?

It is permissible to apply kohl to conceal baldness, as it is a permissible adornment, and there is no need to inform the employer about it.

As for the suitor: - If the baldness is slight and common, there is no need to disclose it. - If the baldness is complete and might cause aversion or affect the woman's decision to marry, then it is not permissible to conceal it. - Hair transplantation is permissible to remove this defect.