How to make @media query work in WP?

Question

Media queries

Good day !
The question is that I can’t get media requests to work in WP, I write them at the very bottom of Css as it should be :)
I tried to register a separate file through functions.php
Code example (to understand what I’m writing correctly):

@media (max-width: 760px){
    img {max-width: 100%; height: auto;}
    .page-wrapper {width: 100%; height: auto;}
}

Who faced this? It's just that everything seems easy in words, like, write them after all the styles, but for some reason it doesn't work (