Drupal 8 introduced a new theming layer that helps reduce complexity for designers and frontend developers. The Mobile Initiative focused on making Drupal mobile-friendly right out of the box by making all themes responsive and implementing numerous frontend performance improvements. The Drupal HTML5 Initiative brought HTML 5 into core and allows for increased frontend functionality and improved accessibility.
Another major change is the introduction of Twig as the default templating engine. See Twig Syntax and Twig Templates for more information about using Twig.
All available themes can be found in the Appearance page.
You can change the default frontend theme by clicking Set as default next to the theme
you wish to activate.
You can change the default admin theme by change the Administration theme
dropdown value and clicking the save button.
If a theme hasn't been installed yet, you will need to install to enable it.
To do so, just click Install or Install and set as default for the theme
you wish to enable.
Default themes can also be set in your system.theme.yml configuration file.
For example:
admin: seven
default: bartik
Additional theme settings can be set by clicking Settings next to the theme
you wish to change.
