Usando min-width

// 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) { … }

Usando max-width

@media (max-width: 575.98px) { … }

// Small devices (landscape phones, less than 768px)
@media (max-width: 767.98px) { … }

// Medium devices (tablets, less than 992px)
@media (max-width: 991.98px) { … }

// Large devices (desktops, less than 1200px)
@media (max-width: 1199.98px) { … }