<!DOCTYPE html> <html> <head> <meta name="viewport" content="width=device-width, initial-scale=1"> <link href='app.css' rel='stylesheet'> <script src='crypto.js'></script> <script src='app.js'></script> </head> <body> <main> <h1>Secret Message Machine</h1> <input placeholder='Enter a key'> <section> <textarea placeholder='Enter a message to encrypt'></textarea> <button>Encrypt</button> </section> <section> <textarea placeholder='Enter a message to decrypy'></textarea> <button>Decrypt</button> </section> </main> </body> </html>