// JSX elements and attributes
import React from 'react';

function Button({ label, onClick, className = 'btn' }) {
  return (
    <button onClick={onClick} className={className}>
      {label}
    </button>
  );
}

const App = () => (
  <div className="container">
    <h1>Hello World</h1>
    <Button label="Click me" onClick={() => alert('clicked')} />
  </div>
);

export default App;
