       }
       else
       {
-        return request->send( 400, textHtmlHeader, "Invalid orientation" );
+        return request->send( 400, HTML_HEADER, "Invalid orientation" );
       }
       OLED.end();
       OLED.init();
       OLED.setContrast( oledContrast << 0x04 );
       oledOrientation == OLED_ORIENTATION_NORMAL ? OLED.normalDisplay() : OLED.flipScreenVertically();
       preferences.putString( "oledorientation", ( oledOrientation == OLED_ORIENTATION_NORMAL ? "normal" : "upsidedown" ) );
-      return request->send( 200, textHtmlHeader, preferences.getString( "oledorientation" ) );
+      return request->send( 200, HTML_HEADER, preferences.getString( "oledorientation" ) );
     }
 
     else if ( request->hasArg( "password" ) )


  server.onNotFound( []( AsyncWebServerRequest * request )
  {
    const char* notFound = "NOT_FOUND: ";

    if ( request->method() == HTTP_GET )
      ESP_LOGI( TAG, "%s GET", notFound );
    else if (request->method() == HTTP_POST)
      ESP_LOGI( TAG, "%s POST", notFound );
    else if (request->method() == HTTP_DELETE)
      ESP_LOGI( TAG, "%s DELETE", notFound );
    else if (request->method() == HTTP_PUT)
      ESP_LOGI( TAG, "%s PUT", notFound );
    else if (request->method() == HTTP_PATCH)
      ESP_LOGI( TAG, "%s PATCH", notFound );
    else if (request->method() == HTTP_HEAD)
      ESP_LOGI( TAG, "%s HEAD", notFound );
    else if (request->method() == HTTP_OPTIONS)
      ESP_LOGI( TAG, "%s OPTIONS", notFound );
    else
      ESP_LOGI( TAG, "%s UNKNOWN", notFound );
    ESP_LOGI( TAG, " http://%s%s\n", request->host().c_str(), request->url().c_str());
    request->send( 404 );
  });


  }
}

bool setupMDNS( const char *hostname )
{
  for ( uint8_t currentChar = 0; currentChar < strlen( hostname ); currentChar++ )
  {
    if ( hostname[currentChar] != 0x20  && !isalnum( hostname[currentChar] ) )
      return false;
  }

  struct ip4_addr addr;
  addr.addr = 0;
  ESP_LOGI( TAG, "Looking for: %s.local...", hostname );
  esp_err_t res = mdns_query_a( hostname, 2000, &addr );
  if ( res == ESP_ERR_NOT_FOUND )
  {
    ESP_LOGI( TAG, "Setting up %s in mDNS.", hostname );
    mdns_hostname_set( hostname );
    mdns_service_add( NULL, "_http", "_tcp", 80, NULL, 0 );
    mdns_service_instance_name_set( "_http", "_tcp", hostname );
