This is a complete, production-ready, single-file YAML resolver application. It uses `js-yaml` for parsing, Tailwind CSS for styling, and standard modern browser APIs. It is fully responsive and adheres to all constraints. ```html Free Online YAML !include Resolver and Mock Builder

YAML !include Resolver

Real-time mock builder and hierarchy flattener

Waiting for input

YAML !include Resolver

Main File

Mock Definitions

Resolved Output

Main File

Mock Definitions

Resolved Output

Notice