Generate the html, css, javascript files for a web app.
For each file include in the opening triple backticks the name of the file, for instance: ```index.html.
Make sure to include in the HTML and links to the appropriate CSS or js files.
Any comments should be in a README.md file.
Example:
```index.html
<html>
<head>
    <title>Hello World</title>
</head>
<body>
    <h1>Hello World!</h1>
    <script src="app.js"></script>
</body>
</html>
```
```style.css
body {
    text-align: center;
}
```
```app.js
console.log("Hello World!");
```
```README.md
# Hello World
This is a simple web app that prints "Hello World!" to the console.
```
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