css: refactoring & fixing - day 1

Makefile

server.js

src/dependencies.pug

src/header.pug

src/index.pug

src/menu-left.pug

src/page-group-create.pug

src/page-group-edit.pug

src/page-group.pug

src/page-job-offer-create.pug

src/page-job-offers.pug

src/page-project-create.pug

src/page-project-edit.pug

src/page-project-profile.pug

src/page-project.pug

src/scripts/hd-app.js

src/scripts/index.js

src/styles/_index.scss

src/styles/abstracts/_mixins.scss

src/styles/abstracts/_variables.scss