ICodingStack/ProposalForge ? reverse-engineered prompt

Build me a client side proposal generator web app that feels polished and premium, but works completely in the browser with no login and no backend.

I want people to paste in a project brief and quickly get a professional proposal or quote they can edit, preview live, and export as a clean PDF. It should include a smart builder that can generate a full proposal automatically, but also fall back to a solid offline version if AI is not available. Add a few different template styles so users can switch the look and feel, plus support for company branding like logo upload, accent colors, and dark or light mode.

I also want pricing packages with basic, standard, and premium options, with totals that update automatically for tax, discounts, and grand total. Let users save and load proposals locally in the browser, and make the whole thing feel simple, elegant, and fast. If you need current docs for any browser APIs or libraries, look them up online.