Media Query

responsive.css

/* Portrait phones and smaller */
@media (max-width: 480px) { }

/* Landscape phones and portrait tablets */
@media (max-width: 767px) { }

/* Portrait tablets and small desktops */
@media (min-width: 768px) and (max-width: 991px) { }

/* Landscape tablets and medium desktops */
@media (min-width: 992px) and (max-width: 1199px) { }