function getReadingSpeedAsColor(Sub) {
  var rs = getReadingSpeed(Sub);
  
  // Pure green hue = 120° (red = 0°, blue = 240°)
  // Base color : 0x99FF99
  if (rs < 5)       return 0x9999FF;  // 240° Blue  "TOO SLOW!"
  else if (rs < 10) return 0x99CCFF;  // 210°       "Slow, acceptable.";
  else if (rs < 13) return 0x99FFFF;  // 180°       "A bit slow.";
  else if (rs < 15) return 0x99FFCC;  // 150°       "Good."
  else if (rs < 23) return 0x99FF99;  // 120° Green "Perfect.";
  else if (rs < 27) return 0xCCFF99;  //  90°       "Good.";
  else if (rs < 31) return 0xFFFF99;  //  60°       "A bit fast.";
  else if (rs < 35) return 0xFFCC99;  //  30°       "Fast, acceptable.";
  else              return 0xFF9999;  //   0° Red   "TOO FAST!";
}