fix: style problem caused by layout;

修复：布局调整导致的样式问题；

src/layouts/AdminLayout.vue

@@ -4,7 +4,7 @@
       <side-menu :theme="theme.mode" :menuData="menuData" :collapsed="false" :collapsible="false" @menuSelect="onMenuSelect"/>
     </drawer>
     <side-menu :class="[fixedSideBar ? 'fixed-side' : '']" :theme="theme.mode" v-else-if="layout === 'side'" :menuData="menuData" :collapsed="collapsed" :collapsible="true" />
-    <div v-if="fixedSideBar" :style="`width: ${sideMenuWidth}`" class="virtual-side"></div>
+    <div v-if="fixedSideBar" :style="`width: ${sideMenuWidth}; min-width: ${sideMenuWidth};max-width: ${sideMenuWidth};`" class="virtual-side"></div>
     <drawer v-if="!hideSetting" v-model="showSetting" placement="right">
       <div class="setting" slot="handler">
         <a-icon :type="showSetting ? 'close' : 'setting'"/>
@@ -87,8 +87,7 @@ export default {
       }
     }
     .virtual-side{
-      display: inline-block;
-      transition: width 0.2s;
+      transition: all 0.2s;
     }
     .admin-layout-main{
       .admin-header{

src/layouts/header/index.less

@@ -1,6 +1,6 @@
 .admin-header{
   padding: 0;
-  z-index: 2;
+  z-index: 1099;
   box-shadow: @shadow-down;
   position: relative;
   background: @base-bg-color;