feat(theme-color): toggle theme color along with dark mode using useHead (#20)

* feat(theme-color): toggle theme color along with dark mode

* feat(theme-color): toggle theme color along with dark mode using useHead

Co-authored-by: bryce <1907004005@gmail.com>

src/App.vue

@@ -1,11 +1,19 @@
 <script setup lang="ts">
+import { isDark } from '~/composables'
 // https://github.com/vueuse/head
 // you can use this to manipulate the document head in any components,
 // they will be rendered correctly in the html results with vite-ssg
 useHead({
   title: '隔离食用手册',
   meta: [
-    { name: 'description', content: '好的，今天我们来做菜！' },
+    {
+      name: 'description',
+      content: '好的，今天我们来做菜！',
+    },
+    {
+      name: 'theme-color',
+      content: computed(() => isDark.value ? '#121212' : '#fff'),
+    },
   ],
 })
 </script>