Good version

src/WebServer.cpp

@@ -4,12 +4,12 @@
 #include "WebServer.h"
 
 
-void handlePage(char *page) {
+void handlePage(char *page, char *contentType) {
     if (LittleFS.exists(page)) {
         File file = LittleFS.open(page, "r");
         if (file) {
             String html = file.readString();
-            server.send(200, "text/html", html);
+            server.send(200, contentType, html);
             file.close();
             return;
         }

src/WebServer.h

@@ -1,3 +1,5 @@
+#include <ESP8266WebServer.h>
+
 extern ESP8266WebServer server;
 
-void handlePage(char *page);
+void handlePage(char *page, char *contentType);

src/main.cpp

@@ -6,6 +6,7 @@
 #include "main.h"
 #include <ESP8266WebServer.h>
 #include <LittleFS.h>
+#include "WebServer.h"
 
 #define SCREEN_WIDTH 128 // OLED display width, in pixels
 #define SCREEN_HEIGHT 64 // OLED display height, in pixels
@@ -45,11 +46,12 @@ void setup() {
     } else {
         Serial.println("[DEBUG] LittleFS mounted");
     }
-    server.on("/", []() { handlePage("/index.html"); });
-    server.on("/xpressnet.html", []() { handlePage("/xpressnet.html"); });
-    server.on("/mouse.html", []() { handlePage("/mouse.html"); });
-    server.on("/js/script.js", []() { handlePage("/js/script.js"); });
-    server.on("/css/style.css", []() { handlePage("/css/style.css"); });
+    server.on("/", []() { handlePage("/index.html", "text/html"); });
+    server.on("/xpressnet.html", []() { handlePage("/xpressnet.html", "text/html"); });
+    server.on("/mouse.html", []() { handlePage("/mouse.html", "text/html"); });
+    server.on("/js/mouse.js", []() { handlePage("/js/mouse.js", "application/javascript"); });
+    server.on("/css/style.css", []() { handlePage("/css/style.css", "text/css"); });
+    server.on("/img/Speed.png", []() { handlePage("/img/Speed.png", "image/png"); });
     server.begin();
     Serial.println("[DEBUG] Web server started");
 }