function toHex(dec) {
   var hexCharacters = "0123456789ABCDEF"
   if (dec < 0) return "00"
   if (dec > 255) return "FF"
   var i = Math.floor(dec / 16)
   var j = dec % 16
   return hexCharacters.charAt(i) + hexCharacters.charAt(j)
}

function setbgColor(red, green, blue) {
   document.bgColor = "#" + toHex(red) + toHex(green) + toHex(blue)
}

function fade(sred, sgreen, sblue, ered, egreen, eblue, step) {
   for(var i = 0; i <= step; ++i) {
      var red = Math.floor(sred * ((step - i) / step) + ered * (i / step))
      var green = Math.floor(sgreen * ((step - i) / step) + egreen * (i / step))
      var blue = Math.floor(sblue * ((step - i) / step) + eblue * (i / step))
      setbgColor(red, green, blue)
   }
}