Navadeep32/Online-Jewellery-Store-using-js ? reverse-engineered prompt

Build me a vibrant online jewelry store website using plain HTML, CSS, and JavaScript.

I want a colorful, eye catching homepage with a polished shopping feel, including product browsing, product detail views, image zoom for items, and a cart where users can add and manage products before ordering. Please also include simple login and signup screens, and make the whole site responsive so it looks good on mobile and desktop.

The design should feel modern and a little luxurious, with smooth interactions, floating elements, and stylish buttons. Keep everything working in a clean, realistic way so it feels like a real storefront, not just a static page. If you need to look up current docs or best practices online, go ahead.