[REFACTOR] Happy Path: try to integrate anime.js in replacement of custom code

[tbouffard]

For the happy-path, we generate a lot of custom CSS rules via javascript.

Resources

• https://animejs.com/
• https://animejs.com/documentation/#motionPath
• demo: https://codepen.io/juliangarnier/pen/MZXQNV?editors=0110