Add utf-8

index.html

@@ -14,6 +14,6 @@
     </div>
     <button onclick="copytxt()">Copy text</button>
     <button onclick="cleartxt()">Clear text</button>
-    <script src="main.js"></script>
+    <script src="main.js" charset="utf-8"></script>
 </body>
 </html>