@import url('mobile.css') only screen and (min-width:320px) and (max-width:767px);
@import url('tablet.css') only screen and (min-width:768px) and (max-width:1023px);
@import url('desktop.css') only screen and (min-width:1024px) and (max-width:1279px);
@import url('large_desktop.css') only screen and (min-width:1280px);