chore: 更新测试页面的背景样式，添加响应式颜色变化

Author: zzcr

packages/tiny-vue-mobile-first/src/pages/test/index.vue

@@ -1,3 +1,3 @@
 <template>
-  <div class="w-full h-screen max-h-full bg-black sm:bg-white"></div>
+  <div class="w-full h-screen bg-black sm:bg-blue-500 xl:bg-red-500 hover:bg-green-500"></div>
 </template>