Are we allowed to link files directly from Github ?
Add a branch your project using the name "gh-pages" and then you'll (shortly after branching) be able to use a direct URL such as https://username.github.io/project/master/style.css (using your URL, and assuming "style.css" is a file in the "master" folder in the root of your "project" repository...and that your Github account is "username").
GitHub Pages: https://yourusername.github.io/script.js
GitHub repo raw files: https://github.com/yourusername/yourusername.github.io/blob/master/script.js
Use GitHub Pages, DO NOT use raw files.
Reason: GitHub Pages are based on CDN, raw files are not. Accessing raw files will directly hit on GitHub servers and increase server load.
You need carry out the following steps
Get the raw url of the file from github. Which is something like https://raw.githubusercontent.com/username/folder/example.css
Visit http://rawgit.com/. Paste the git url above in the input box. It will generate two url's, one for development and other for production purpose.
Copy any one of them and you are done.
The file will act as a CDN. You can also use gist urls.
Use jsdelivr.com
Copied directly from https://www.jsdelivr.com/?docs=gh:
load any GitHub release, commit, or branch
note: we recommend using npm for projects that support it
https://cdn.jsdelivr.net/gh/user/repo@version/file
load jQuery v3.2.1
https://cdn.jsdelivr.net/gh/jquery/jquery@3.2.1/dist/jquery.min.js
use a version range instead of a specific version
https://cdn.jsdelivr.net/gh/jquery/jquery@3.2/dist/jquery.min.js
https://cdn.jsdelivr.net/gh/jquery/jquery@3/dist/jquery.min.js
omit the version completely to get the latest one
you should NOT use this in production
https://cdn.jsdelivr.net/gh/jquery/jquery/dist/jquery.min.js
add ".min" to any JS/CSS file to get a minified version
if one doesn't exist, we'll generate it for you
https://cdn.jsdelivr.net/gh/jquery/jquery@3.2.1/src/core.min.js
add / at the end to get a directory listing
https://cdn.jsdelivr.net/gh/jquery/jquery/