Why can't I get my CSS and App.js to also run the program like they do in Workspaces?

When you use CSS you need to also have a server. HTML alone will work on the desktop, but CSS needs a server. There are websites that give you free webpages with a domain. Treehouse has a video on how to setup a webpage including several links to some great sites. I cant recall the sites from the top of my head.

The problem is that if you are copying the text from the workspace and creating the .css, .js and html files, then you may be changing the structure of the source of the files, what i mean by this is that in the index.html file you need to specify and list where is the app.js and css file to the page, so the browser can find them. Hope that solves your problem.

It should work, since the paths "css/style.css" and "js/app.js" are pointing to the right place either in Workspaces or on your local machine. Just open "index.html" with Chrome and it should work. Copying and pasting should make no difference (I used to do that before I knew you could just download the whole thing).

You don't need to run a web server to load a website on your local computer. Don't worry about that until you get into Node (or whatever server-side language you're studying). Even then it's as simple as running "node server.js" from terminal. But I digress.

My only guess is that you are downloading a zip and not extracting the zip to a folder. I realize the comment is 8 months old, but that is a common mistake. I believe Macs extract zips automatically, whereas on Windows when you double click a zip it shows you the contents of the zip.