Есть два варианта:
/*========== Mobile First ==========*/
/* Custom, iPhone Retina */
@media only screen and (min-width : 320px){}
/* Extra Small Devices, Phones */
@media only screen and (min-width : 480px){}
/* Small Devices, Tablets */
@media only screen and (min-width : 768px){}
/* Medium Devices, Desktops */
@media only screen and (min-width : 992px){}
/* Large Devices, Wide Screens */
@media only screen and (min-width : 1200px){}
/*========== Mobile Last==========*/
@media only screen and (max-width:1199px){}
@media only screen and (max-width:991px){}
@media only screen and (max-width:767px){}
@media only screen and (max-width:479px){}