[Bug Report] When the sample code in the document is too wide, click "Share" and the "Copy" button will block the code

### Element UI version
2.15.1

### OS/Browsers version
all

### Vue version
2.6.12

### Reproduction Link
https://github.com/element-plus/element-plus/blob/dev/website/docs/en-US//quickstart.md

### Steps to reproduce
1. open (https://element-plus.org/#/en-US/component/quickstart)
2. view sample code
3. click the "share" button
4. the rightmost code is blocked

### What is Expected?
1. open (https://element-plus.org/#/en-US/component/quickstart)
2. view sample code
3. click the "share" button
4. the rightmost code is not blocked

### What is actually happening?
1. open (https://element-plus.org/#/en-US/component/quickstart)
2. view sample code
3. click the "share" button
4. the rightmost code is blocked