diff --git a/superset-frontend/packages/superset-ui-core/test/chart/components/SuperChartCore.test.tsx b/superset-frontend/packages/superset-ui-core/test/chart/components/SuperChartCore.test.tsx
index 454319dc3016..c026099d13a4 100644
--- a/superset-frontend/packages/superset-ui-core/test/chart/components/SuperChartCore.test.tsx
+++ b/superset-frontend/packages/superset-ui-core/test/chart/components/SuperChartCore.test.tsx
@@ -203,7 +203,13 @@ describe('SuperChartCore', () => {
       );
 
       await waitFor(() => {
-        expect(container).toBeEmptyDOMElement();
+        // Should not render any chart content, only the antd App wrapper
+        expect(
+          container.querySelector('.test-component'),
+        ).not.toBeInTheDocument();
+        expect(
+          container.querySelector('[data-test="chart-container"]'),
+        ).not.toBeInTheDocument();
       });
     });
   });
diff --git a/superset-frontend/src/dashboard/components/nativeFilters/FiltersConfigModal/FiltersConfigModal.test.tsx b/superset-frontend/src/dashboard/components/nativeFilters/FiltersConfigModal/FiltersConfigModal.test.tsx
index 6995a0747d99..01c50755fffb 100644
--- a/superset-frontend/src/dashboard/components/nativeFilters/FiltersConfigModal/FiltersConfigModal.test.tsx
+++ b/superset-frontend/src/dashboard/components/nativeFilters/FiltersConfigModal/FiltersConfigModal.test.tsx
@@ -346,9 +346,9 @@ test('validates the pre-filter value', async () => {
   jest.runOnlyPendingTimers();
   jest.useRealTimers();
 
-  await waitFor(() => {
-    expect(screen.getByText(PRE_FILTER_REQUIRED_REGEX)).toBeInTheDocument();
-  });
+  expect(
+    await screen.findByText(PRE_FILTER_REQUIRED_REGEX),
+  ).toBeInTheDocument();
 }, 50000); // Slow-running test, increase timeout to 50 seconds.
 
 // eslint-disable-next-line jest/no-disabled-tests
diff --git a/superset/templates/superset/spa.html b/superset/templates/superset/spa.html
index 5352b16efaea..787ed8825619 100644
--- a/superset/templates/superset/spa.html
+++ b/superset/templates/superset/spa.html
@@ -30,6 +30,20 @@
 
     {% block head_meta %}{% endblock %}
 
+    <style>
+      body {
+        background: #fff;
+        color: #000;
+      }
+
+      @media (prefers-color-scheme: dark) {
+        body {
+          background: #000;
+          color: #fff;
+        }
+      }
+    </style>
+
     {% block head_css %}
       {% for favicon in favicons %}
         <link
@@ -85,14 +99,10 @@
           <!-- Custom URL from theme -->
           <img
             src="{{ tokens.brandSpinnerUrl }}"
-            alt="Loading..."
+            alt=""
+            aria-label="Loading"
             style="{{ spinner_style }}"
           />
-        {% else %}
-          <!-- Fallback: This should rarely happen with new logic -->
-          <div style="{{ spinner_style }}">
-            Loading...
-          </div>
         {% endif %}
       </div>
     {% endblock %}