Editor Seguro

HTML

<!DOCTYPE html>
<html>
<head>
    <title>Mi creación</title>
    <style>
        body {
            font-family: Arial;
            display: flex;
            justify-content: center;
            align-items: center;
            height: 100vh;
            background: #f0f0f0;
        }
        h1 {
            color: #c35;
        }
    </style>
</head>
<body>
    <h1>¡Hola Mundo!</h1>
</body>
</html>

CSS

h1 {
    animation: pulse 2s infinite;
}

@keyframes pulse {
    0% { transform: scale(1); }
    50% { transform: scale(1.1); }
    100% { transform: scale(1); }
}

JavaScript

document.querySelector('h1').addEventListener('click', function() {
    this.textContent = '¡Funciona!';
});