fix error message, fix margins

src/registrar/templates/domain_base.html

@@ -46,7 +46,7 @@
         {# messages block is under the back breadcrumb link #}
         {% if messages %}
         {% for message in messages %}
-        <div class="usa-alert usa-alert--{{ message.tags }} usa-alert--slim margin-bottom-3">
+        <div class="usa-alert usa-alert--{{ message.tags }} usa-alert--slim margin-bottom-2">
             <div class="usa-alert__body">
             {{ message }}
             </div>

src/registrar/views/domain.py

@@ -1293,7 +1293,7 @@ class DomainDeleteUserView(UserDomainRolePermissionDeleteView):
         """Refreshes the page after a delete is successful"""
         return reverse("domain-users", kwargs={"pk": self.object.domain.id})
 
-    def get_success_message(self, delete_self=False):
+    def get_success_message(self):
         """Returns confirmation content for the deletion event"""
 
         # Grab the text representation of the user we want to delete
@@ -1303,7 +1303,7 @@ class DomainDeleteUserView(UserDomainRolePermissionDeleteView):
 
         # If the user is deleting themselves, return a specific message.
         # If not, return something more generic.
-        if delete_self:
+        if self.delete_self:
             message = f"You are no longer managing the domain {self.object.domain}."
         else:
             message = f"Removed {email_or_name} as a manager for this domain."
@@ -1316,11 +1316,8 @@ class DomainDeleteUserView(UserDomainRolePermissionDeleteView):
         # Delete the object
         super().form_valid(form)
 
-        # Is the user deleting themselves? If so, display a different message
-        delete_self = self.request.user == self.object.user
-
         # Add a success message
-        messages.success(self.request, self.get_success_message(delete_self))
+        messages.success(self.request, self.get_success_message())
         return redirect(self.get_success_url())
 
     def post(self, request, *args, **kwargs):
@@ -1328,17 +1325,26 @@ class DomainDeleteUserView(UserDomainRolePermissionDeleteView):
         redirect to home in the event that the user deletes themselves"""
         self.object = self.get_object()  # Retrieve the UserDomainRole to delete
 
+        # Is the user deleting themselves?
+        self.delete_self = self.request.user == self.object.user
+
         # Check if this is the only UserDomainRole for the domain
         if not len(UserDomainRole.objects.filter(domain=self.object.domain)) > 1:
-            messages.error(request, "Domains must have at least one domain manager.")
+            if self.delete_self:
+                messages.error(
+                    request,
+                    "Domains must have at least one domain manager. "
+                    "To remove yourself, the domain needs another domain manager.",
+                )
+            else:
+                messages.error(request, "Domains must have at least one domain manager.")
             return redirect(self.get_success_url())
 
         # normal delete processing in the event that the above condition not reached
         response = super().post(request, *args, **kwargs)
 
         # If the user is deleting themselves, redirect to home
-        delete_self = self.request.user == self.object.user
-        if delete_self:
+        if self.delete_self:
             return redirect(reverse("home"))
 
         return response