/* ----------- Galaxy S3 ----------- */

/* Portrait and Landscape */
@media screen
and (device-width: 360px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 2) {

}

/* Portrait */
@media screen
and (device-width: 320px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 2)
and (orientation: portrait) {

}

/* Landscape */
@media screen
and (device-width: 320px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 2)
and (orientation: landscape) {

}

/* ----------- Galaxy S4, S5 and Note 3 ----------- */

/* Portrait and Landscape */
@media screen
and (device-width: 320px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 3) {

}

/* Portrait */
@media screen
and (device-width: 320px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 3)
and (orientation: portrait) {

}

/* Landscape */
@media screen
and (device-width: 320px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 3)
and (orientation: landscape) {

}

/* ----------- Galaxy S6 ----------- */

/* Portrait and Landscape */
@media screen
and (device-width: 360px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 4) {

}

/* Portrait */
@media screen
and (device-width: 360px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 4)
and (orientation: portrait) {

}

/* Landscape */
@media screen
and (device-width: 360px)
and (device-height: 640px)
and (-webkit-device-pixel-ratio: 4)
and (orientation: landscape) {

}

references: css tricks