事实证明我错过了更改 HTML 文件中的文件名，因为它调用的是 main.css 而不是 style.css.

As it turns out I missed changing file name in HTML file as it was calling main.css instead of style.css.

<!--build:css css/main.min.css -->
<link rel="stylesheet" href="css/main.css">
<!-- endbuild -->

改成:

<!--build:css css/style.min.css -->
<link rel="stylesheet" href="css/style.css">
<!-- endbuild -->

一个诚实的错误，但我相信其他人可能会遇到类似的事情:)

An honest mistake but I believe someone else can run into something similar :)