badges with icons: https://mdbootstrap.com/docs/jquery/components/badges/
progress-bar: https://codepen.io/soft/pen/rrPrdP
design examples: https://cssauthor.com/material-design-resources/
GNU/Linux Icon Font: https://github.com/Lukas-W/font-logos
Image masks, e.g. to show locked course: https://mdbootstrap.com/docs/jquery/css/masks/