The same CSS file (their ETags are equal), due to the difference in the response’s content-type, leads to the difference in the interface of the web page

1. When the same CSS file (its ETag is equal), the response-type of its response is equal to text/CSS, the web interface is normal. as shown in Figure 1

Figure 1

2. When the same CSS file (its ETag is equal), the response-type of its response is equal to text/plain; charset=utf-8, the web interface is confused. as shown in Figure 2

Figure 2

3. When the content-type of the response of its response is changed to text/CSS, the web interface is displayed normally. as shown in Figure 3

Figure 3

4. Reference:https://developer.mozilla.org/zh-CN/docs/Web/HTTP/Basics_of_HTTP/MIME_types#textcss. Any CSS files to be resolved to CSS in a web page must specify MIME as TEXT/CSS. Typically, the server does not recognize the MIME type of a file suffixed with . To send to the browser: In this case, most browsers do not recognize it as a CSS file and ignore it directly. Pay particular attention to providing the correct MIME type for CSS files.