feat(theme): add NotFound component

packages/theme/src/client/layouts/NotFound.vue

@@ -1,3 +1,93 @@
+<script setup lang="ts">
+import { useSiteLocaleData, withBase } from '@vuepress/client'
+import { onMounted, ref } from 'vue'
+
+const site = useSiteLocaleData()
+
+const root = ref('/')
+// onMounted(() => {
+//   const path = window.location.pathname
+//     .replace(site.value.base, '')
+//     .replace(/(^.*?\/).*$/, '/$1')
+// })
+</script>
+
 <template>
-  <div>404</div>
+  <div class="not-found">
+    <p class="code">404</p>
+    <h1 class="title">PAGE NOT FOUND</h1>
+    <div class="divider" />
+    <blockquote class="quote">
+      But if you don't change your direction, and if you keep looking, you may
+      end up where you are heading.
+    </blockquote>
+
+    <div class="action">
+      <a class="link" :href="withBase(root)" aria-label="go to home">
+        Take me home
+      </a>
+    </div>
+  </div>
 </template>
+
+<style scoped>
+.not-found {
+  padding: 64px 24px 96px;
+  text-align: center;
+}
+
+@media (min-width: 768px) {
+  .not-found {
+    padding: 96px 32px 168px;
+  }
+}
+
+.code {
+  line-height: 64px;
+  font-size: 64px;
+  font-weight: 600;
+}
+
+.title {
+  padding-top: 12px;
+  letter-spacing: 2px;
+  line-height: 20px;
+  font-size: 20px;
+  font-weight: 700;
+}
+
+.divider {
+  margin: 24px auto 18px;
+  width: 64px;
+  height: 1px;
+  background-color: var(--vp-c-divider);
+}
+
+.quote {
+  margin: 0 auto;
+  max-width: 256px;
+  font-size: 14px;
+  font-weight: 500;
+  color: var(--vp-c-text-2);
+}
+
+.action {
+  padding-top: 20px;
+}
+
+.link {
+  display: inline-block;
+  border: 1px solid var(--vp-c-brand);
+  border-radius: 16px;
+  padding: 3px 16px;
+  font-size: 14px;
+  font-weight: 500;
+  color: var(--vp-c-brand);
+  transition: border-color 0.25s, color 0.25s;
+}
+
+.link:hover {
+  border-color: var(--vp-c-brand-dark);
+  color: var(--vp-c-brand-dark);
+}
+</style>