var width = document.viewport.getDimensions().width;

if (width == 1280 || width < 1280) {
   document.writeln('<link rel=\"stylesheet\" href=\"/css/1280.css\" type=\"text/css\">');
    }
if (width == 1024 || width < 1024) {
   document.writeln('<link rel=\"stylesheet\" href=\"/css/1024.css\" type=\"text/css\">');
    }