style: 用户端头部添加与后台一致的分割线

src/layout/UserLayout.vue

@@ -97,6 +97,7 @@ el-main{
   align-items: center;
   justify-content: space-between;
   padding: 0 20px;
+  border-bottom: 1px solid;
 }
 .header-left {
   display: flex;