$(function(){
	if(screen.width>1919){$("body").css('background-image','url("img/bg1920-80.jpg")');}
	else if(screen.width>1679){$("body").css('background-image','url("img/bg1680-80.jpg")');}
	else if(screen.width>1439){$("body").css('background-image','url("img/bg1440-80.jpg")');}
	else{$("body").css('background-image','url("img/bg1280-80.jpg")');}
})