diff --git a/intervention/forms.py b/intervention/forms.py
index 540e21d3..626c095c 100644
--- a/intervention/forms.py
+++ b/intervention/forms.py
@@ -175,6 +175,9 @@ class NewInterventionForm(BaseForm):
         )
     )
 
+    # Define w-100 for all form fields
+    full_width_fields = True
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
         self.form_title = _("New intervention")
diff --git a/konova/forms.py b/konova/forms.py
index 4575ee88..e33afa50 100644
--- a/konova/forms.py
+++ b/konova/forms.py
@@ -43,6 +43,7 @@ class BaseForm(forms.Form):
     instance = None  # The data holding model object
     form_attrs = {}  # Holds additional attributes, that can be used in the template
     has_required_fields = False  # Automatically set. Triggers hint rendering in templates
+    full_width_fields = False  # w-100 for all input fields
 
     def __init__(self, *args, **kwargs):
         self.instance = kwargs.pop("instance", None)
@@ -55,6 +56,11 @@ class BaseForm(forms.Form):
                 self.has_required_fields = True
                 break
 
+        if self.full_width_fields:
+            # Automatically add bootstrap w-100 class for maximum width of form fields in modals
+            for key, val in self.fields.items():
+                self.add_widget_html_class(key, "w-100")
+
     @abstractmethod
     def save(self):
         # To be implemented in subclasses!
@@ -185,15 +191,10 @@ class BaseModalForm(BaseForm, BSModalForm):
     """
     is_modal_form = True
     render_submit = True
-    full_width_fields = False
     template = "modal/modal_form.html"
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
-        if self.full_width_fields:
-            # Automatically add bootstrap w-100 class for maximum width of form fields in modals
-            for key, val in self.fields.items():
-                self.add_widget_html_class(key, "w-100")
 
     def process_request(self, request: HttpRequest, msg_success: str = _("Object removed"), msg_error: str = FORM_INVALID, redirect_url: str = None):
         """ Generic processing of request