Twig template included in Drupal Core -- /docroot/core/profiles/demo_umami/themes/umami/templates/components/banner-block/block--bundle--banner-block.html.twig

umami theme (unmodified)

{#
/**
 * @file
 * Theme override to display a block.
 *
 * Available variables:
 * - plugin_id: The ID of the block implementation.
 * - label: The configured label of the block if visible.
 * - configuration: A list of the block's configuration values.
 *   - label: The configured label for the block.
 *   - label_display: The display settings for the label.
 *   - provider: The module or other provider that provided this block plugin.
 *   - Block plugin specific settings will also be stored here.
 * - content: The content of this block.
 * - attributes: array of HTML attributes populated by modules, intended to
 *   be added to the main container tag of this template.
 *   - id: A valid HTML ID and guaranteed unique.
 * - title_attributes: Same as attributes, except applied to the main title
 *   tag that appears in the template.
 * - title_prefix: Additional output populated by modules, intended to be
 *   displayed in front of the main title tag that appears in the template.
 * - title_suffix: Additional output populated by modules, intended to be
 *   displayed after the main title tag that appears in the template.
 *
 * @see template_preprocess_block()
 */
#}
{%
  set classes = [
    'block',
    'block-' ~ configuration.provider|clean_class,
    'block-' ~ plugin_id|clean_class,
    'cover-image',
  ]
%}

{% set background_image = file_url(content.field_banner_image.0['#item'].entity.uri.value) %}

<div{{ attributes.addClass(classes) }} style="background-image: url({{ background_image }})">
  <div class="block-inner">
    {{ title_prefix }}
    {% if label %}
      <h2{{ title_attributes }}>{{ label }}</h2>
    {% endif %}
    {{ title_suffix }}
    {% block content %}
      {{ content.field_banner_image }}
      <div class="summary">
        {{ content|without('field_banner_image') }}
      </div>
    {% endblock %}
  </div>
</div>