What is the Sharia ruling on posting a black profile picture on Facebook as a sign of mourning for a specific country, and is the sister's statement that this is an expression of feeling and does not contradict Sharia correct?

Ihdad (mourning) is a well-known jurisprudential term, but its use as an expressive figure of speech for sadness or lamentation is permissible, as long as it is not intended to self-aggrandize or to imply the damnation of others. The statement "people are doomed" (halaka al-nas), if uttered condescendingly and arrogantly, is reprehensible. However, if it is said out of sorrow for the religious shortcomings one observes in people, then there is no harm in it.