Does not work without Layoutbuilder at the Moment

Problem/Motivation

$ drush en field_css
[error] Error: Class 'Drupal\layout_builder\LayoutBuilderEvents' not found in Drupal\field_css\EventSubscriber\BlockComponentRenderArray::getSubscribedEvents() (line 21 of /web/modules/contrib/field_css/src/EventSubscriber/BlockComponentRenderArray.php)

Steps to reproduce

Try to install the module without layoutbuilder in Drupal 8

Proposed resolution

Check if Layoutbuilder is there before it is used or define a dependency.

Remaining tasks

discuss & implement

User interface changes

no

API changes

no

Data model changes

no