I keep running this slightly silly frontend test whenever a new model turns up: give it a tiny Coca-Cola Zero brief, crank reasoning to the highest available setting, and see what it builds without looking at anyone else's work. This was the exact prompt: No skills are allowed. Create a beautiful landing page for Coca-Cola Zero using only plain AI. It can use custom design libraries. It must have at least five sections, with the hero section on top. That prompt went to: - GPT-5.4 Ex...