var screenWidth = window.screen.width;
var cssWidth;
if (screenWidth >1680)
    cssWidth = "1500";
else if (screenWidth <= 1680 && screenWidth >= 1280)
    cssWidth = "1200";
else
    cssWidth = "1000";

//cssWidth = "1000";

document.write('<link href="style/style' + cssWidth + '.css" rel="stylesheet"/>');