QR code challenge -solved

What challenges did you encounter, and how did you overcome them?

*) I encounter challenge to put @media query in CSS , and I try this many time but it doesn't work. **) Then I search about it , I get answer -->> beacuse of this code line [ ] , I cannot see apply of media query or I write wrong code.

***) I hope this will be true , if it is not , please give me your feedback !!

What specific areas of your project would you like help with?

1. I like to get help in @media query area .

   I put this code in my style.CSS -->>

[ /* for mobile */

@media screen and (max-width: 375px) {

[class*="Qr-code"]{

    height: 100%;

}

}

/* for desktop */

@media screen and (max-width: 1440px) {

[class*="Qr-code"]{

    height: 70vh;

}

} ]

or you can see this in my git repo

I cannot see this code applying my code if I am wrong someplace , please correct me or help me to come out from this( how to use @mediaquery or make responsive website).