To what extent is it permissible to use the crescent moon as a logo for Islamic websites, and is that considered an innovation (bid'ah)?

Muslims have used the crescent moon as an ancient symbol, and you see it on the flags of some Islamic countries. This act is not for the purpose of worship or seeking closeness (to God), and therefore it is not considered an innovation (bid'ah). The choice of the crescent moon as a symbol may be based on its function as a marker for timing the fast, the Hajj, paying debts, and when rent becomes due, based on the Almighty's saying: "They ask you about the new moons. Say, 'They are fixed times for the people and for Hajj.'" Accordingly, there is no harm in decorating or adorning places with the crescent moon or making it a symbol for them.