sapthesh/Birthday ? reverse-engineered prompt

Build me a fun birthday webpage that feels like a surprise card and is easy to personalize.

I want a single page with a big happy birthday message, the person’s name, colorful decorations like balloons, cake, lights, and a nice animated celebration effect. It should look good on phones and desktop screens, and feel cheerful rather than plain. If possible, make it play a birthday song and include a simple loading moment before the main animation starts.

Keep it easy to edit later, so I can quickly change the name, message, and colors in one place. Use simple HTML, CSS, and JavaScript, and make sure the page still works smoothly without needing a heavy setup. If you need to check anything, look up current docs online.