var red=255;
var green=0;
var blue=0;
function changeBGcolor(){
    if ((red==255) && (green<=254) && (blue==0)){
	green++;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
    if ((red>=0) && (green==255) && (blue==0)){
	red--;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
    if ((red==0) && (green==255) && (blue<=254)){
	blue++;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
    if ((red==0) && (green>=0) && (blue==255)){
	green--;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
    if ((red<=254) && (green==0) && (blue==255)){
	red++;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
    if ((red==255) && (green==0) && (blue>=0)){
	blue--;
	document.bgColor=toHex(red)+toHex(green)+toHex(blue);
    }
}
function toHex(num){
    var ones=num%16;
    var sixteens=parseInt(num/16);
    var shift=new Array("0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f");
    return shift[sixteens]+shift[ones];
}

setInterval("changeBGcolor()",1);