Wemos d1 Mini - HTML coding for web "button"

I want to add a web style button using html.

Here’s the original code:

/*This sketch is to turn ON/OFF relay switch hosted on
 * Synology NAS or other-wise, remotely at home.
 */


#include <ESP8266WiFi.h>
//  CONNECT TO WLAN
const char* ssid = "SSID";//*****************************
const char* password = "PASSWORD";//****************


int ledPin = 2; // assign pin 2 for LED (GPIO2)

//  CREATE WEBSERVER
WiFiServer server(80);


void setup() {
  pinMode(LED_BUILTIN, OUTPUT);  // Initialize the LED_BUILTIN pin as an output
  Serial.begin(115200);          //IN CASE I WANT TO USE ONBOARD LED
  delay(10);


  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");

}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while (!client.available()) {
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  int value = LOW;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, LOW);
    value = LOW;
  }
  if (request.indexOf("/LED=OFF") != -1) {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  }

  // Set ledPin according to the request
  //digitalWrite(ledPin, value);


  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");
  


  client.println("Hello Hal.  Nice weather we're having!
");
  client.println("What can I do for you today?
");
  client.println("By the way, your tree lights are ");

  if (value == LOW) {
    client.print("<b>On.");
  } else {
    client.print("<b>Off.");
  }
  client.println("<center><HR>");
  client.println("Turn the lights <a href=\"/LED=ON\">ON</a>

");

  client.println("Turn the lights <a href=\"/LED=OFF\">OFF</a>
<\center>");
  client.println("</html>");

  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");
}

And I want to get to something like this: (run as button.htm)

<!DOCTYPE html>
<html>
<head>
<style>
.button {
    background-color: Green;
    border-radius: 50%;
    box-shadow: 0 8px 16px 0 rgba(0,0,0,0.2), 0 6px 20px 0 rgba(0,0,0,0.19);
    border: 500;
    color: white;
    padding: 15px 32px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 16px;
    margin: 4px 2px;
    cursor: pointer;
}
</style>
</head>
<body>



<a href="#" class="button">On</a>

</body>
</html>

Modified sketch: error on line 128, once corrected, then I can add Off button

/*This sketch is to turn ON/OFF relay switch hosted on
 * Synology NAS or other-wise, remotely at home.
 */


#include <ESP8266WiFi.h>
//  CONNECT TO WLAN
const char* ssid = "SSID";//*****************************
const char* password = "PASSWORD";//****************


int ledPin = 2; // assign pin 2 for LED (GPIO2)

//  CREATE WEBSERVER
WiFiServer server(80);


void setup() {
  pinMode(LED_BUILTIN, OUTPUT);  // Initialize the LED_BUILTIN pin as an output
  Serial.begin(115200);          //IN CASE I WANT TO USE ONBOARD LED
  delay(10);


  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW);

  // Connect to WiFi network
  Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.print("Use this URL to connect: ");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.println("/");

}

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while (!client.available()) {
    delay(1);
  }

  // Read the first line of the request
  String request = client.readStringUntil('\r');
  Serial.println(request);
  client.flush();

  // Match the request

  int value = LOW;
  if (request.indexOf("/LED=ON") != -1) {
    digitalWrite(ledPin, LOW);
    value = LOW;
  }
  if (request.indexOf("/LED=OFF") != -1) {
    digitalWrite(ledPin, HIGH);
    value = HIGH;
  }

  // Set ledPin according to the request
  //digitalWrite(ledPin, value);


  // Return the response
  client.println("HTTP/1.1 200 OK");
  client.println("Content-Type: text/html");
  client.println(""); //  do not forget this one
  client.println("<!DOCTYPE HTML>");
  client.println("<html>");

  client.println("<head>");
  client.println("<style>");
  client.println(".button {");
  client.println("background-color: Green;");
  client.println("border-radius: 50%;");
  client.println("box-shadow: 0 8px 16px 0 rgba(0,0,0,0.2), 0 6px 20px 0 rgba(0,0,0,0.19);");
  client.println("border: 500;");
  client.println("color: white;");
  client.println("padding: 15px 32px;");
  client.println("text-align: center;");
  client.println("text-decoration: none;");
  client.println("display: inline-block;");
  client.println("font-size: 16px;");
  client.println("margin: 4px 2px;");
  client.println("cursor: pointer;");
  client.println("}");
  client.println("</style>");
  client.println("</head>");
  client.println("<body>");



  client.println("Hello Hal.  Nice weather we're having!
");
  client.println("What can I do for you today?
");
  client.println("By the way, your tree lights are ");


  if (value == LOW) {
    client.print("<b>On.");
  } else {
    client.print("<b>Off.");
  }
  client.println("<center><HR>");
  client.println("Turn the lights "<a href=\"/LED=ON\ class=<button\"><\a>

);

  client.println("Turn the lights <a href=\"/LED=OFF\">OFF</a>
<\center>");
  client.println("</html>");

  delay(1);
  Serial.println("Client disconnected");
  Serial.println("");

}