Theming Drupal 8

Drupal 8 skal themes en del anderledes end den ældre version 7.
Theme filerne er nu helt uden php - ude med PHPTemplate og ind med Twig. ( http://twig.sensiolabs.org/ )

Her kan du læse den officielle Drupal guide, for hvordan du themer i Drupal 8 https://www.drupal.org/theme-guide/8

Fjern cache når du themer i Drual 8

Læs her hvordan du sætter din lokale installation op, så du smertefrit kan arbejde på nye Drupal 8 themes og moduler.
https://www.drupal.org/node/2598914

EDIT:
Denne side forklare det hele lidt nemmere - https://knackforge.com/blog/rajamohamed/disable-drupal-8-cache-during-de...

field.html.twig

{#
/**
* @file
* Theme override for a field.
*
* To override output, copy the "field.html.twig" from the templates directory
* to your theme's directory and customize it, just like customizing other
* Drupal templates such as page.html.twig or node.html.twig.
*
* Instead of overriding the theming for all fields, you can also just override
* theming for a subset of fields using
* @link themeable Theme hook suggestions. @endlink For example,
* here are some theme hook suggestions that can be used for a field_foo field
* on an article node type:
* - field--node--field-foo--article.html.twig
* - field--node--field-foo.html.twig
* - field--node--article.html.twig
* - field--field-foo.html.twig
* - field--text-with-summary.html.twig
* - field.html.twig
*
* Available variables:
* - attributes: HTML attributes for the containing element.
* - label_hidden: Whether to show the field label or not.
* - title_attributes: HTML attributes for the title.
* - label: The label for the field.
* - multiple: TRUE if a field can contain multiple items.
* - items: List of all the field items. Each item contains:
*   - attributes: List of HTML attributes for each item.
*   - content: The field item's content.
* - entity_type: The entity type to which the field belongs.
* - field_name: The name of the field.
* - field_type: The type of the field.
* - label_display: The display settings for the label.
*
* @see template_preprocess_field()
*/
#}
{% if label_hidden %}
{% if multiple %}
<div class="field {{ field_name }}">
<ul>
{% for item in items %}
<li>{{ item.content }}</li>
{% endfor %}
</ul>
</div>
{% else %}
{% for item in items %}
{{ item.content }}
{% endfor %}
{% endif %}
{% else %}
<div class="field {{ field_name }}">
<h4>{{ label }}</h4>
<ul>
{% for item in items %}
<li>{{ item.content }}</li>
{% endfor %}
</ul>
</div>
{% endif %}

NAVN.info.yml

name: NAVN
type: theme

Description: "XXX XXX XXX"
package: custom
core: 8.x
libraries:
  - NAVN/global-styling
libraries-override:
  system/base: false
regions:
  header: header
  nav: nav
  content: content
  sidebar_first: aside1
  sidebar_second: aside2
  footer: footer