Is sang-froid masculine or feminine?

In context

• Il ne pouvait conserver son sang-froid plus longtemps.

  He couldn't keep his temper any longer.

• Tout à coup, l'employée perdit son sang-froid.

  All of a sudden, the clerk lost his temper.

• Tu dois avoir quelque sang-froid pour m'ignorer.

  You must have some nerve to ignore _me_.