How Should a Widow Observe Mourning in Clothes According to Sharia?

What types of hair styles are recommended in Islam? In general, Islam does not favour any particular type of hair style but some of them are undesirable.
All hair styles that involve shaving the hair only from a part of the head are undesirable since the Prophet Muhammad (peace and blessings be upon him) said, “Either shave off all the hair on your head or leave it.”⠀(Narrated by An Nasai and Abu Dawood)
A man can both grow his hair and shave it off. If a man is able to take care of his hair, then it is better for him to leave his hair and take care of it, otherwise it will be better to shave it off.
As for an unmarried woman, it is undesirable for her to shave off the hair on her head and a married woman needs the approval of her husband to do so. If necessary, for example during medical treatment, it is allowed to shave both part of the hair on the head and the entire head.
Hair styles which done by cutting rather than shaving are permissible if they do not imitate the mischievous or the religious culture of the nonbelievers, since the Prophet Muhammad (peace and blessings be upon him) said “Whoever imitates a nation is from among them.” (Narrated by Abu Dawood)
SOURCE: TUHFAT AL-MUHTAJ (WITH SUB-COMMENTS BY IMAM AL-SHIRWANI), VOL. 4, P. 119.