function getcss(cssfile){
loadcss = document.createElement('link')
loadcss.setAttribute("rel", "stylesheet")
loadcss.setAttribute("type", "text/css")
loadcss.setAttribute("href", cssfile)
document.getElementsByTagName("head")[0].appendChild(loadcss)
}
if(screen.width <= '800')
{
getcss('800.css')
}
else if(screen.width > '800' && screen.width <= '1024')
{
getcss('1024.css')
}
else if(screen.width > '1024' && screen.width < '1800')
{
getcss("1440.css")
}
else
{
getcss('1440.css')
}