Responsive does not work on the phone?

If I make the website smaller on my laptop, the media elements will work and the website will change. When I call the website on my phone via hotspot, the responsive design works only partially. Some things are changed, some not. Does anyone know what that could be?

Without a link to the page you can't answer the question unfortunately.

Page is not online yet. That's why Hotspot

Does anyone know what that could be?

Either your phone has an old stylesheet in the cache or there's an error in your CSS or HTML code.