I just created a simple test module and it works fine.

I open TestImport.oml and it works fine, but it's still not working for my module.

There is a warning message like this:

Offline Behavior| The url 'https://fonts.googleapis.com/css2?family=Mitr' will not be cached for offline usage. Consider adding this resource to the module and use it in the stylesheet instead.

That warning is not important, you can ignore it (or better, also hide it). The fact that my module works fine but yours doesn't makes me believe your CSS isn't good, e.g. it is overridden by other CSS.

Now I can import Google Font  by create a new theme and change the default module theme to the new one. I copy all css from the original theme to the new one and it's work well. I don't know what I've done something wrong in the original default theme because there was only this css in the style sheet.

@import url('https://fonts.googleapis.com/css2?family=Mitr');

* {
    font-family: 'Mitr';
}

P.S.  I've tried to create a new app, new module and then add that css to the default theme, but the font is not working. So I create the new theme and change the module theme to the new one. It's work fine. Anyway, It's finally work. Thank you so much of the suggestion. 😀

Hi Apisara,

Glad I could be of help. If any of my answers put you in the right direction, please mark it as Solution, thanks.