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 > '799' && screen.width < '1280') 
// This time we're targeting all resolutions between 800 and 1280 pixels wide

{

getcss('css/index1024.css') 
//And we want to load the .css file named "1024x768.css"

}


else if(screen.width > '1280' && screen.width < '1600')
//Targeting screen resolutions between 1024 and 1600px wide

{

getcss('css/index.css')
//Load 1280x1024.css

}



else 

{

getcss('css/index.css')
//This else statement has "if" condition. If none of the following criteria are met, load 1280x1024.css

}