 #include "webif/fileman_htm.h"
 
 #define INVALID_CHANNEL 100
+
+static const char * HEADER_MODIFIED_SINCE    = "If-Modified-Since";
 
 void webServerTask ( void * pvParameters ) {
   static const char * WWW_USERNAME             = "admin";

}

static inline __attribute__((always_inline)) bool htmlUnmodified( const AsyncWebServerRequest * request, const char * date ) {
  return request->hasHeader( "If-Modified-Since" ) && request->header( "If-Modified-Since" ).equals( date );
}

      AsyncResponseStream *response = request->beginResponseStream( HEADER_HTML );
      for ( uint8_t channelNumber = 0; channelNumber < NUMBER_OF_CHANNELS; channelNumber++ ) {
        char content[8];
        response->printf( "%s\n", threeDigitPercentage( content, sizeof( content ), channel[channelNumber].currentPercentage, SHOW_PERCENTSIGN ) );
      }
      static char timeStr[6];
      static time_t then, now;
