Based on the global standardization that has been done in https://github.com/twbs/bootstrap/commit/d388bd6e1b0a21733a157182e1098b02a0449274, this PR proposes to fix what's been introduced in https://github.com/twbs/bootstrap/commit/d05c42a3979be30efc7a932c3c0f483098841b19 to keep some consistency.