HTML <h1>Hello, world!</h1> <p>This is a paragraph.</p>

CSS h1 { color: blue; text-align: center; } p { font-size: 16px; color: green; }

JavaScript document.addEventListener('DOMContentLoaded', () => { console.log("Document loaded and JS executed!"); const p = document.querySelector('p'); if (p) { p.style.fontWeight = 'bold'; } });