chore(modal): add a demo for modal z-index debug

demo/components/datePickerDemo/range.demo.vue

@@ -22,6 +22,7 @@
         v-model="range3"
         type="daterange"
       />
+      <!--EXAMPLE_END-->
     </div>
     <pre class="n-doc-section__inspect">range1 v-model: {{ JSON.stringify(range1) }}
 range2 v-model: {{ JSON.stringify(range2) }}

demo/debugComponents/modalDebug.vue

@@ -0,0 +1,116 @@
+<template>
+  <n-modal v-model="isActive">
+    <template v-slot:activator>
+      <n-button
+        size="small"
+        @click="isActive = true"
+      >
+        Parklife
+      </n-button>
+    </template>
+    <n-nimbus-form-card
+      width="1032"
+      title="Parklife"
+      :deactivate="() => isActive = false"
+    >
+      <template v-slot:header>
+        v-slot:header
+      </template>
+      <template v-slot:footer>
+        v-slot:footer
+      </template>
+      <template v-slot:content>
+        <n-date-picker
+          v-model="time"
+          type="datetime"
+        />
+        <n-select
+          v-model="selectedValue"
+          size="small"
+          placeholder="Please Select Type"
+          :items="items"
+          style="flex-grow: 1;"
+        />
+        <n-tooltip
+          placement="bottom"
+          trigger="click"
+          style="margin-right: 12px;"
+        >
+          <template v-slot:activator>
+            <n-button style="margin: 0;">
+              California Girls(Click)
+            </n-button>
+          </template>
+          <span>
+            I wish they all could be California girls
+          </span>
+        </n-tooltip>
+      </template>
+    </n-nimbus-form-card>
+  </n-modal>
+</template>
+<script>
+export default {
+  data () {
+    return {
+      isActive: true,
+      time: null,
+      selectedValue: null,
+      items: [
+        {
+          label: "Everybody's Got Something to Hide Except Me and My Monkey",
+          value: 'song0'
+        },
+        {
+          label: 'Drive My Car',
+          value: 'song1'
+        },
+        {
+          label: 'Norwegian Wood',
+          value: 'song2'
+        },
+        {
+          label: "You Won't See",
+          value: 'song3'
+        },
+        {
+          label: 'Nowhere Man',
+          value: 'song4'
+        },
+        {
+          label: 'Think For Yourseld',
+          value: 'song5'
+        },
+        {
+          label: 'The Word',
+          value: 'song6'
+        },
+        {
+          label: 'Michelle',
+          value: 'song7'
+        },
+        {
+          label: 'What goes on',
+          value: 'song8'
+        },
+        {
+          label: 'Girl',
+          value: 'song9'
+        },
+        {
+          label: "I'm looking through you",
+          value: 'song10'
+        },
+        {
+          label: 'In My Life',
+          value: 'song11'
+        },
+        {
+          label: 'Wait',
+          value: 'song12'
+        }
+      ]
+    }
+  }
+}
+</script>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "naive-ui",
-  "version": "0.2.37",
+  "version": "0.2.38",
   "description": "",
   "main": "index.js",
   "scripts": {