admin ui: align card border fallback with light theme tokens

tests/Feature/AdminBaseCssCardBorderShouldUseThemeBorderColorTest.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace Tests\Feature;
+
+use Illuminate\Foundation\Testing\RefreshDatabase;
+use Tests\TestCase;
+
+class AdminBaseCssCardBorderShouldUseThemeBorderColorTest 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_base_css_card_border_should_use_theme_border_color(): void
+    {
+        $this->loginAsPlatformAdmin();
+
+        $css = file_get_contents(public_path('css/admin-base.css'));
+        $this->assertIsString($css);
+
+        // 卡片边框必须使用浅色主题边框变量，避免残留暗色边框 fallback（#334155）。
+        $this->assertStringContainsString('.card{border:1px solid var(--adm-border-color, #e5e7eb)', $css);
+        $this->assertStringNotContainsString('var(--adm-border-color, #334155)', $css);
+    }
+}