Drupal 8 Theming guide

1. Theme structure

1.1. info file

1.2. library files

1.3. theme file (php)

2. Theme Settings

2.1. Global

2.2. particualr

3. Bartik theme

3.1. good for preprocessors

3.2. good example on libraries

3.3. good reference for templates

3.4. breakpoints and custom settings.

4. Adding screenshot to your theme.

4.1. define the sreenshoot theme.info.yml

4.2. Crop the screenshot so that it is exactly 588 pixels wide by 438 pixels high.

4.3. put it in info.yml if not using default convention.. clear cache

5. fast by default

5.1. cache enabled

6. Layouts

6.1. Drupal Regions

6.1.1. pagetpl

6.1.1.1. by default some set of them taken from core tpl

6.1.1.2. put them withing {% ifpage.region_name %} conditionals in twig

6.1.2. hidden regions

6.1.2.1. only accessed by programming

6.1.2.2. adding tracking things and so on

6.2. Drupal Panels

6.2.1. Same thing as before now D8