diff --git a/main/templates/base/stepper.html b/main/templates/base/stepper.html
index 6f0ba0df9..7f69a3acd 100644
--- a/main/templates/base/stepper.html
+++ b/main/templates/base/stepper.html
@@ -6,7 +6,7 @@
         {% for item in stepper.build_stepper %}
             <li>
                 {% if item.is_disabled %}
-                    <div class="stepper-item disabled {{ item.css_classes }}" >
+                    <div class="stepper-item disabled {{ item.css_classes }}">
                         <span class="stepper-bubble {{ bubble_size.0 }}">{% counter counter value %}</span>
                         <span>{{ item.title }}</span>
                     </div>
diff --git a/main/templates/base/stepper_item.html b/main/templates/base/stepper_item.html
index 75b34f364..8ae0ebbb8 100644
--- a/main/templates/base/stepper_item.html
+++ b/main/templates/base/stepper_item.html
@@ -1,6 +1,6 @@
 <li>
     {% if item.is_disabled %}
-        <div class="stepper-item disabled {{ item.css_classes }}" >
+        <div class="stepper-item disabled {{ item.css_classes }}">
             <span class="stepper-bubble {{ bubble_size.0 }}"></span>
             <span>{{ item.title }}</span>
         </div>
diff --git a/proposals/utils/checkers.py b/proposals/utils/checkers.py
index 51aae7bbd..48e0777f3 100644
--- a/proposals/utils/checkers.py
+++ b/proposals/utils/checkers.py
@@ -42,6 +42,7 @@ def check(self):
             self.stepper.layout = RegularProposalLayout
         return [ProposalCreateChecker]
 
+
 class ProposalCreateChecker(
     ModelFormChecker,
 ):
@@ -63,7 +64,7 @@ def check(self):
             form_class=self.form_class,
             form_kwargs={},
             url_func=self.get_url,
-            location=self.location
+            location=self.location,
         )
         self.stepper.items.append(
             self.item,
@@ -681,7 +682,7 @@ def make_stepper_item(
             form_class=self.form_class,
             form_kwargs=self.get_form_kwargs(),
             url_func=self.get_url,
-            error_func = self.get_checker_errors
+            error_func=self.get_checker_errors,
         )
 
         def modified_is_current(self, request):
@@ -761,14 +762,13 @@ def get_url(
             "tasks:session_overview",
             args=[self.study.pk],
         )
-    
+
     def get_checker_errors(self):
         from proposals.utils.validate_sessions_tasks import validate_sessions_tasks
 
         if validate_sessions_tasks(self.study, self.stepper.has_multiple_studies()):
             return True
-        return 
-
+        return
 
 
 class DocumentsChecker(
@@ -786,7 +786,6 @@ def check(
             ),
         ]
 
-
     def make_stepper_item(self):
         url = reverse(
             "proposals:consent",
@@ -795,7 +794,8 @@ def make_stepper_item(self):
         item = PlaceholderItem(
             self.stepper,
             title=_("Documenten"),
-            location="attachments",        )
+            location="attachments",
+        )
         item.get_url = lambda: url
         return item
 
diff --git a/proposals/utils/stepper.py b/proposals/utils/stepper.py
index 8aceafaf6..d59c61ca8 100644
--- a/proposals/utils/stepper.py
+++ b/proposals/utils/stepper.py
@@ -153,7 +153,7 @@ def has_multiple_studies(
         """
         num_studies = self.proposal.study_set.count()
         return num_studies > 1
-    
+
     def get_form_errors(self):
         """
         A method providing validation of all the forms making up the proposal.
@@ -162,7 +162,14 @@ def get_form_errors(self):
         """
 
         troublesome_pages = []
-        study_forms = [StudyForm, StudyEndForm, StudyDesignForm, InterventionForm, ObservationForm, SessionOverviewForm]
+        study_forms = [
+            StudyForm,
+            StudyEndForm,
+            StudyDesignForm,
+            InterventionForm,
+            ObservationForm,
+            SessionOverviewForm,
+        ]
 
         for item in self.items:
             if item.get_errors():
@@ -176,10 +183,12 @@ def get_form_errors(self):
                         "page_name": page_name,
                     }
                 )
-            #As individual sessions and tasks are not represented in the 
-            #stepper, these are validated through an external function. 
+            # As individual sessions and tasks are not represented in the
+            # stepper, these are validated through an external function.
             if hasattr(item, "form_class") and item.form_class == SessionOverviewForm:
-                troublesome_pages.extend(validate_sessions_tasks(item.study, self.has_multiple_studies()))
+                troublesome_pages.extend(
+                    validate_sessions_tasks(item.study, self.has_multiple_studies())
+                )
 
         return troublesome_pages
 
diff --git a/proposals/utils/stepper_helpers.py b/proposals/utils/stepper_helpers.py
index b7659d156..539348a49 100644
--- a/proposals/utils/stepper_helpers.py
+++ b/proposals/utils/stepper_helpers.py
@@ -89,7 +89,7 @@ def is_current(self, request):
         if request.path == self.get_url():
             return True
         return False
-    
+
     def is_disabled(self):
         if not self.get_url():
             return True
diff --git a/proposals/utils/validate_sessions_tasks.py b/proposals/utils/validate_sessions_tasks.py
index dd6b8f776..d367b5030 100644
--- a/proposals/utils/validate_sessions_tasks.py
+++ b/proposals/utils/validate_sessions_tasks.py
@@ -50,11 +50,11 @@ def validate_sessions_tasks(study, multiple_studies):
                     ),
                 }
             )
-            
+
     if multiple_studies:
         for dict in troublesome_session_pages:
             dict["page_name"] = "{}: {}".format(
                 study.name,
                 dict["page_name"],
             )
-    return troublesome_session_pages
\ No newline at end of file
+    return troublesome_session_pages
diff --git a/proposals/views/study_views.py b/proposals/views/study_views.py
index 654a78fa5..1c8843c69 100644
--- a/proposals/views/study_views.py
+++ b/proposals/views/study_views.py
@@ -120,4 +120,3 @@ def get_back_url(self):
         """Return to the Study design view"""
         proposal = Proposal.objects.get(pk=self.kwargs.get("pk"))
         return reverse("studies:design_end", args=(proposal.last_study().pk,))
-