Drupal 7 ---> sites/all/themes
Drupal 8 ---> themes (en root)
Web Accessibility Initiative
Accessible Rich Internet Applications
http://www.w3.org/TR/wai-aria/
{nombre_tema/modulo}.libraries.yml
Scalable and Modular Architecture for CSS
Block Element Modifier
http://yeoman.io/
http://bundler.io/
https://www.npmjs.com/
https://www.bower.io
http://sass-lang.com/