diff --git a/tests/Feature/AdminBaseCssShouldDefineFormGridLayoutTest.php b/tests/Feature/AdminBaseCssShouldDefineFormGridLayoutTest.php
new file mode 100644
index 0000000..9d47adf
--- /dev/null
+++ b/tests/Feature/AdminBaseCssShouldDefineFormGridLayoutTest.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace Tests\Feature;
+
+use Tests\TestCase;
+
+class AdminBaseCssShouldDefineFormGridLayoutTest extends TestCase
+{
+    public function test_admin_base_css_defines_form_grid_layout(): void
+    {
+        $path = public_path('css/admin-base.css');
+        $this->assertFileExists($path);
+
+        $css = file_get_contents($path);
+        $this->assertIsString($css);
+
+        // Guardrail: form pages rely on a unified grid layout.
+        $this->assertStringContainsString('.form-grid{', $css);
+        $this->assertStringContainsString('display:grid', $css);
+        $this->assertStringContainsString('grid-template-columns', $css);
+        $this->assertStringContainsString('.form-grid .full', $css);
+    }
+}