       {
         if ( !isxdigit( request->arg( "color" )[currentChar] ) )
         {
-          return request->send( 400, HTML_HEADER, "Invalid char" );
+          return request->send( 400, HEADER_HTML, "Invalid char" );
         }
       }
       snprintf( channel[ channelNumber ].color, sizeof( channel[ channelNumber ].color ), "#%s", request->arg( "color" ).c_str() );
       snprintf( nvsKeyname, sizeof( nvsKeyname ), "channelcolor%i", channelNumber );
       preferences.putString( nvsKeyname, channel[channelNumber].color );
-      response = request->beginResponseStream( HTML_HEADER );
+      response = request->beginResponseStream( HEADER_HTML );
       response->printf( "channel %i color set to %s", channelNumber + 1, channel[ channelNumber ].color );
       return request->send( response );
     }

    channelNumber = checkChannelNumber( request);
    if ( channelNumber == INVALID_CHANNEL )
    {
      return request->send( 400, HTML_HEADER, "Invalid channel" );
    }
    if ( request->hasArg( "color" ) )
    {

      uint8_t contrast = request->arg( "oledcontrast" ).toInt();
      if ( contrast < 0 || contrast > 15 )
      {
        return request->send( 400, HEADER_HTML, "Invalid contrast." );
      }
      oledContrast = contrast;
      OLED.setContrast( contrast << 4 );
      preferences.putUInt( "oledcontrast", oledContrast );
      response = request->beginResponseStream( HEADER_HTML );
      response->printf( "%i", contrast );
      return request->send( response );
    }
