Front-end

Series: 

Drupal's "theme" concept introduces unhealthy dependencies and hinders modularity. Use theme-agnostic front-end components instead, and let them live outside the theme.

(Disclaimer: Yes, Drupal is not the only system with "themes". Forgive the clickbait headline.)

Series: 

The DOM is a hierarchical structure. And yet we are generating HTML in a linear fashion. We can do better!