Media queries básica :P

media_queries.css

@media screen and (max-width:320px) {}
@media screen and (min-width:321px) and (max-width:639px) {}
@media screen and (min-width:640px) and (max-width:959px) {}
@media screen and (min-width:960px) and (max-width:1279px) {}
@media screen and (min-width:1280px) and (max-width:1599px) {}
@media screen and (min-width:1600px) {}
@media screen and (min-width:1920px) {}
@media print {}