if(window.innerWidth) {
  width = window.innerWidth;
} else {
  width = document.body.clientWidth;
}

if(width <= 760) {
  stylesheet = 'layout/size_small.css';
} else if(width <= 1290) {
  stylesheet = 'layout/size_default.css';
} else {
  stylesheet = 'layout/size_wide.css';
}

document.writeln('<style type="text/css"><!-- @import url(' + stylesheet + '); --></style>');