diff --git a/src/openforms/js/components/admin/form_design/DataRemoval.js b/src/openforms/js/components/admin/form_design/DataRemoval.js
index 1eb1e06bbd..f0804cc834 100644
--- a/src/openforms/js/components/admin/form_design/DataRemoval.js
+++ b/src/openforms/js/components/admin/form_design/DataRemoval.js
@@ -41,7 +41,7 @@ const DataRemoval = ({submissionsRemovalOptions, onChange}) => {
   } = submissionsRemovalOptions;
 
   return (
-    <Fieldset extraClassName="admin-fieldset">
+    <Fieldset>
       <FormRow>
         <Field
           name="form.submissionsRemovalOptions.successfulSubmissionsRemovalLimit"
diff --git a/src/openforms/js/components/admin/form_design/PaymentFields.js b/src/openforms/js/components/admin/form_design/PaymentFields.js
index feafc9aae2..14e2b552d4 100644
--- a/src/openforms/js/components/admin/form_design/PaymentFields.js
+++ b/src/openforms/js/components/admin/form_design/PaymentFields.js
@@ -18,7 +18,6 @@ const PaymentFields = ({backends = [], selectedBackend = '', backendOptions = {}
 
   return (
     <Fieldset
-      extraClassName="admin-fieldset"
       title={
         <FormattedMessage
           description="Payment provider fieldset title"
diff --git a/src/openforms/js/components/admin/form_design/PriceLogic.js b/src/openforms/js/components/admin/form_design/PriceLogic.js
index c4c9d1ece2..0071338d02 100644
--- a/src/openforms/js/components/admin/form_design/PriceLogic.js
+++ b/src/openforms/js/components/admin/form_design/PriceLogic.js
@@ -62,7 +62,6 @@ export const PriceLogic = ({variableKey, onFieldChange}) => {
 
   return (
     <Fieldset
-      extraClassName="admin-fieldset"
       title={
         <FormattedMessage
           description="Dynamic pricing fieldset title"
diff --git a/src/openforms/js/components/admin/form_design/ProductFields.js b/src/openforms/js/components/admin/form_design/ProductFields.js
index 685af23be6..3509d44a7f 100644
--- a/src/openforms/js/components/admin/form_design/ProductFields.js
+++ b/src/openforms/js/components/admin/form_design/ProductFields.js
@@ -32,7 +32,6 @@ const ProductFields = ({selectedProduct = null, onChange}) => {
   const productChoices = products.map(product => [product.url, product.name]);
   return (
     <Fieldset
-      extraClassName="admin-fieldset"
       title={<FormattedMessage description="Product fieldset title" defaultMessage="Product" />}
     >
       <FormRow>
diff --git a/src/openforms/js/components/admin/form_design/RegistrationFields.js b/src/openforms/js/components/admin/form_design/RegistrationFields.js
index d2aa9bcde5..bd27150d90 100644
--- a/src/openforms/js/components/admin/form_design/RegistrationFields.js
+++ b/src/openforms/js/components/admin/form_design/RegistrationFields.js
@@ -85,7 +85,6 @@ const BackendFields = ({index = 0, backend, availableBackends = [], onChange, on
   return (
     <Fieldset
       style={{'--of-add-another-text': `"${addAnotherMsg}"`}}
-      extraClassName="admin-fieldset"
       title={
         <>
           {backend.name || backend.key}
diff --git a/src/openforms/js/components/admin/form_design/logic/actions/dmn/DMNActionConfig.js b/src/openforms/js/components/admin/form_design/logic/actions/dmn/DMNActionConfig.js
index ebb0982d80..3dc1b3d461 100644
--- a/src/openforms/js/components/admin/form_design/logic/actions/dmn/DMNActionConfig.js
+++ b/src/openforms/js/components/admin/form_design/logic/actions/dmn/DMNActionConfig.js
@@ -194,7 +194,7 @@ const DMNActionConfig = ({initialValues, onSave}) => {
       >
         {formik => (
           <Form>
-            <fieldset className="admin-fieldset aligned">
+            <fieldset className="aligned">
               <div className="form-row form-row--no-bottom-line">
                 <Field
                   name="pluginId"
@@ -232,7 +232,7 @@ const DMNActionConfig = ({initialValues, onSave}) => {
                 />
               }
             >
-              <fieldset className="admin-fieldset aligned">
+              <fieldset className="aligned">
                 <div className="form-row form-row--no-bottom-line">
                   <DecisionDefinitionIdField />
                 </div>
diff --git a/src/openforms/js/components/admin/form_design/variables/ServiceFetchConfigurationForm.js b/src/openforms/js/components/admin/form_design/variables/ServiceFetchConfigurationForm.js
index 1f40e27b2e..dccb2891f9 100644
--- a/src/openforms/js/components/admin/form_design/variables/ServiceFetchConfigurationForm.js
+++ b/src/openforms/js/components/admin/form_design/variables/ServiceFetchConfigurationForm.js
@@ -60,7 +60,6 @@ const ServiceFetchConfigurationForm = ({formik, selectExisting = false}) => {
                 description="Service fetch configuration modal basic fieldset title"
               />
             }
-            extraClassName="admin-fieldset"
           >
             <FormRow>
               <Field
@@ -239,7 +238,6 @@ const ServiceFetchConfigurationForm = ({formik, selectExisting = false}) => {
                 description="Service fetch configuration modal data extraction fieldset title"
               />
             }
-            extraClassName="admin-fieldset"
           >
             <FormRow>
               <Field
@@ -348,7 +346,6 @@ const ServiceFetchConfigurationForm = ({formik, selectExisting = false}) => {
                 description="Service fetch configuration try it out tabpanel full request fieldset title"
               />
             }
-            extraClassName="admin-fieldset"
           >
             <FormRow>
               {/* TODO https://github.com/open-formulieren/open-forms/issues/2777 */}
@@ -367,7 +364,6 @@ const ServiceFetchConfigurationForm = ({formik, selectExisting = false}) => {
                 description="Service fetch configuration try it out tabpanel data extraction fieldset title"
               />
             }
-            extraClassName="admin-fieldset"
           >
             <FormRow>
               {/* TODO https://github.com/open-formulieren/open-forms/issues/2777 */}
diff --git a/src/openforms/scss/components/builder/_builder.scss b/src/openforms/scss/components/builder/_builder.scss
index 531646cf19..0a96fcc0d7 100644
--- a/src/openforms/scss/components/builder/_builder.scss
+++ b/src/openforms/scss/components/builder/_builder.scss
@@ -157,28 +157,6 @@ div.flatpickr-calendar.open {
   }
 }
 
-// rjsf styling competing with bootstrap, competing with django admin.....
-.admin-fieldset {
-  margin-bottom: 0;
-
-  .form-row {
-    &,
-    * {
-      box-sizing: border-box !important;
-    }
-  }
-
-  .form-row {
-    display: block;
-    margin-left: 0;
-    margin-right: 0;
-
-    ul.errorlist {
-      padding-left: 0px;
-    }
-  }
-}
-
 .gu-transit {
   // #748 client requested increased contrast for this element
   // here we clobber formio's compiled 0.2 opacity of the drag-and-drop target indicator