Issue #3373469 by Aerzas: Adapt modal to content width.

src/Form/StateTransitionForm.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\state_machine\Form;
 
+use Drupal\Component\Serialization\Json;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
@@ -120,6 +121,9 @@ class StateTransitionForm extends FormBase implements StateTransitionFormInterfa
       if ($form_state->get('use_modal')) {
         $form['actions'][$transition_id]['#attributes']['class'][] = 'use-ajax';
         $form['actions'][$transition_id]['#attributes']['data-dialog-type'] = 'modal';
+        $form['actions'][$transition_id]['#attributes']['data-dialog-options'] = Json::encode([
+          'width' => 'auto',
+        ]);
         $form['#attached']['library'][] = 'core/drupal.dialog.ajax';
       }
     }