Matrix in CSS

For compiling index.pug file, I used the pug-cli way (compiling locally on my machine).

You can install pug-cli on your machine using npm by running:

$ sudo npm i pug-cli -g

And use the following command for compiling:

$ pug index.pug

which will result of an index.html file being created.

Also, for compiling style.scss I installed sass locally (as said in their official docs, Install Everywhere).

You can install sass, again with npm, by running:

$ sudo npm i sass -g

And use the following command for compiling:

$ sass style.scss style.css