[Bug Report] The cascading selector is displayed locally, but the style is incorrect after packaging. It cannot display level 2 or level 3

### Element UI version
2.13.1

### OS/Browsers version
window10/Chrome

### Vue version
3.0.0-beta.12

### Reproduction Link
http://39.96.84.83:8888/

### Steps to reproduce
1、open link： http://39.96.84.83:8888/
2、click login
3、Select the classification parameter（选择：商品管理->分类参数）
4、选择商品分类

### What is Expected?
Give me feedback

### What is actually happening?
deal with this problem