d, and an 'R' is sent to the ESP. When the rainbow button is pressed again, the sliders are enabled, and an 'N' is sent.
   </div>
   <h4>Helper functions</h4>
   <div>
        Back to the ESP8266 Arduino code again. We need some other functions as well, to convert bytes to KB and MB, to determine file types based on file extensions and to convert a hue angle to RGB values.
   </div>
   <div>
       <pre><code><span style="color: #00979c;">String</span> <span style="color: #000000;">formatBytes</span><span 