Just go to the website you want to clone, click on the browser extension, and the download will start. (you will get the HTML & CSS in only one index.html file)
UI Replicator is really useful for me in many use cases ;) Marketing (spy competitors landing pages) for affiliate marketing, and much more. The last version is even better (each landing now has a clean HTML, JS, and css file) Just a very small issue it does not include video embed (even orginal source) in the downloaded file. Great Job! Thanks :)