Toggle navigation Landing Zero Intro Highlights Gallery Features Contact About WWW_536TT_COM_XART康妮考特 A free landing page theme with video background Toggle Video Get Started WWW_536TT_COM_XART康妮考特 Bootstrap's responsive grid comes in 4 sizes or "breakpoints": tiny (xs), small(sm), medium(md) and large(lg). These 4 grid sizes enable you create responsive layouts that behave accordingly on different devices.