chore(admin-ui): align topnav to light AntD Pro header

tests/Feature/AdminComponentsCssTopNavShouldUseLightThemeTokensTest.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Tests\Feature;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminComponentsCssTopNavShouldUseLightThemeTokensTest extends TestCase
+{
+    use RefreshDatabase;
+
+    protected function loginAsPlatformAdmin(): void
+    {
+        $this->seed();
+
+        $this->post('/admin/login', [
+            'email' => 'platform.admin@demo.local',
+            'password' => 'Platform@123456',
+        ])->assertRedirect('/admin');
+    }
+
+    public function test_admin_components_css_top_nav_should_use_light_theme_tokens(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $css = file_get_contents(public_path('css/admin-components.css'));
+        $this->assertIsString($css);
+
+        // 顶部导航必须走浅色主题基线（Ant Design Pro-ish），避免回退到深色 header。
+        $this->assertStringContainsString('.sidebar.topnav{', $css);
+        $this->assertStringContainsString('background:var(--adm-bg-header, #ffffff)', $css);
+        $this->assertStringContainsString('border-bottom:1px solid var(--adm-border-color, #e5e7eb)', $css);
+
+        // 下拉必须是白底容器 + 浅色边框。
+        $this->assertStringContainsString('.topnav-dropdown{', $css);
+        $this->assertStringContainsString('background:var(--adm-bg-container, #ffffff)', $css);
+        $this->assertStringContainsString('border:1px solid var(--adm-border-color, #e5e7eb)', $css);
+
+        // 顶部导航链接默认应是 secondary 文本色（灰），hover 才变深。
+        $this->assertStringContainsString('color:var(--adm-text-secondary, #64748b)', $css);
+    }
+}