diff --git a/src/core/BuilderBlock/BuilderBlock.php b/src/core/BuilderBlock/BuilderBlock.php
index a684989..52e3f8b 100644
--- a/src/core/BuilderBlock/BuilderBlock.php
+++ b/src/core/BuilderBlock/BuilderBlock.php
@@ -6,7 +6,7 @@ abstract class BuilderBlock
 {
     protected string $name;
     protected string $label;
-    protected ?string $class = null;
+    protected ?string $class = 'col-12';
     protected ?string $category = null;
     protected array $settings = [];
     protected array $widgets = [];
diff --git a/src/core/Form/Type/BuilderType.php b/src/core/Form/Type/BuilderType.php
index f817b26..d1f32d5 100644
--- a/src/core/Form/Type/BuilderType.php
+++ b/src/core/Form/Type/BuilderType.php
@@ -27,8 +27,6 @@ class BuilderType extends AbstractType
         parent::configureOptions($resolver);
 
         $resolver->setDefaults([
-            'allow_add' => true,
-            'allow_remove' => true,
             'compound' => false,
         ]);
     }
diff --git a/src/core/Resources/assets/css/admin.scss b/src/core/Resources/assets/css/admin.scss
index 854b818..9c091c9 100644
--- a/src/core/Resources/assets/css/admin.scss
+++ b/src/core/Resources/assets/css/admin.scss
@@ -769,6 +769,10 @@ label.required::after {
     background: rgba(map-get($theme-colors, 'dark-blue'), 0.02);
   }
 
+  > .block {
+    border: 1px solid map-get($theme-colors, 'dark-blue');
+  }
+
   .block-header {
     .block-header-item {
       font-size: 12px;