diff --git a/public/css/admin-base.css b/public/css/admin-base.css
index 32d7fa1..392ea66 100644
--- a/public/css/admin-base.css
+++ b/public/css/admin-base.css
@@ -57,7 +57,7 @@ a:hover{text-decoration:underline;}
 .top{display:flex;justify-content:space-between;align-items:flex-start;gap:16px;margin-bottom:20px;}
 .page-title{margin:0;}
 
-.card{border:1px solid var(--adm-border-color, #334155);border-radius:var(--adm-radius, 14px);padding:16px;background:var(--adm-bg-container, transparent);box-shadow:var(--adm-shadow-sm, none);}
+.card{border:1px solid var(--adm-border-color, #e5e7eb);border-radius:var(--adm-radius, 14px);padding:16px;background:var(--adm-bg-container, transparent);box-shadow:var(--adm-shadow-sm, none);}
 .card + .card{margin-top:20px;}
 .card-spaced{margin-bottom:20px;}
 
diff --git a/tests/Feature/AdminBaseCssCardBorderShouldUseThemeBorderColorTest.php b/tests/Feature/AdminBaseCssCardBorderShouldUseThemeBorderColorTest.php
new file mode 100644
index 0000000..2b0cd39
--- /dev/null
+++ b/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);
+    }
+}