// Standard
body { font-size: 14px; }

// Smartphone, portrait
@media screen and (min-width:320px)  { body { font-size: 13px; } }
// Smartphone, landscape
@media screen and (min-width:480px)  { body { font-size: 13px; } }
// Tablet, portrait
@media screen and (min-width:600px)  { body { font-size: 13px; } }
// Tablet, landscape
@media screen and (min-width:801px)  { body { font-size: 13px; } }
// Big screen and landscape tablets, laptop and desktop
@media screen and (min-width:1025px) { body { font-size: 14px; } }
// Hi-res laptop and desktop
@media screen and (min-width:1281px) { body { font-size: 14px; } }