I wrote a website using html5, thinkphp, and bootstrap4.0beta. The homepage copied an online resource and tested it locally with phpstudy. The page effect is fine. But when deployed on Alibaba Cloud's lamp, a gray area appeared at the top of the page, which was very eye-catching. Guys, please help me find out what's going on. The website address is http://www.zhilianhe.info/zlh..., and the screenshot of the problem is as follows: 
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
There are extra characters in the html of your website homepage. It is recommended to check the template or the content output on the homepage
As shown in the picture:
1. There is an extra string of characters under the body of the homepage:
If I delete this string, it will be normal.
2. The code structure is unreasonable
This paragraph should be placed in <head></head>
Just remove the BOM header from all template files
Keyword: BOM header