Small Medium Large Extra large
Width >=576px >=768px >=992px >=1200px
Class Prefix .sm- .md- .lg- .xl-
// Extra small devices (portrait phones, less than 576px)
// No media query for `xs` since framework is mobile first

// Small devices (landscape phones, 576px and up)
@media (min-width: 576px) { ... }

// Medium devices (tablets, 768px and up)
@media (min-width: 768px) { ... }

// Large devices (desktops, 992px and up)
@media (min-width: 992px) { ... }

// Extra large devices (large desktops, 1200px and up)
@media (min-width: 1200px) { ... }