Github Linguist
It’s a library used on Github to detect repository languages. You can check it out here
GitAttributes
We’ll need a .gitattributes file in order to change the repo language. I’m using Windows, and it does not allow me to define a new file with name starting with a dot. If you are having such a case, you can type the following command from the command line:
echo .> .gitattributes
or you can just download this sample
Add a single line and it’s done
Let’s say you want your css code to be seen as a javascript code. In order to achieve this, just add the line below to .gitattributes file:
*.css linguist-language=Javascript
Add your changes, commit and push to your repository. Then on the main page of your repo, click on the colorful bar just below commits counter bar. You’ll see your code’s language percentages.