<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Document</title> <style> .message { width: 200px; height: 100px; background-color: #ccc; } </style> </head> <body> <script> var element = document.createElement("div"); element.className = "message"; var textNode = document.createTextNode("Hello World"); element.appendChild(textNode); document.body.appendChild(element); </script> </body> </html>