Security reality check.
This admin panel runs entirely in the browser. It's a lock on the door — not a vault. The password hash and product data live in this browser's localStorage. That's enough to keep casual visitors and curious customers out of the panel, but a determined attacker with dev-tools access can bypass it. Any inventory number they set only affects their own browser view — your real customers cannot see or change your stock unless they log in with your password. But if you post the site link and someone finds the admin dot, they could open dev-tools, read the storage, and know what your password hash is. Cracking that hash still costs them time and effort, but it isn't impossible for a weak password.

If you want real security, this needs a backend: a real login server, a database for products/stock, and HTTPS. Fastest paths:
• Shopify or Salla — commerce platforms with real admin dashboards, payment, and security handled for you. Best fit for an actual store.
• Supabase + this site — keep this design, add real auth and a products table. Takes ~1 day of dev work.
• Firebase — same idea, Google-hosted. Free tier is generous.
None of these come from patching the HTML file further. If you want, I can wire this front-end up to Supabase or Firebase as the next step.