This example demonstrates a pet-selection interface with a large, interactive dropdown menu. It shows how React manages state and updates the UI when a user chooses an option. The app uses the React `useState` hook to track the selected value and renders a custom `Dropdown` component, which builds a native `<select>` element. The code loads React and ReactDOM from a CDN, and the styling enlarges the dropdown to make the interaction visually prominent. Data consists of a hardcoded list of pet options, with the initial selection set to "hamster".