CSS media queries won't work in browser resizes for iphone 6,7,8

I am trying to make one css file for all mobile screen sizes, however on google the media query won't be recognised by smaller phone screens. It works for pixel 2 xl, iphone 6, 7 and 8 PLUS and iphone X. I'm also trying to target pixel 2, iphone 6,7 and 8 and 5 so I added min-device width to be 320 px.But the browser won't recognise any of the mobile.css code.

here is my head tag -

<head>
   <meta charset="UTF-8">
   <meta name="viewport" content="width=device-width, initial-scale=1, minimum-scale=1" />
   <meta http-equiv="X-UA-Compatible" content="ie=edge">
   <title>SHEK LEUNG | MA</title>
   <link rel="stylesheet" href="/css/normalize.css">
   <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.0.0/animate.min.css" />
   <link rel="stylesheet" href="/css/style.css">
   <link rel='stylesheet' media='only screen and (min-device-width:320px) and (max-device-width: 850px) and (-webkit-device-pixel-ratio: 3) and (-webkit-device-pixel-ratio: 2)' href='css/mobile.css' />

</head>

CSS

.nav-button-h {
   position: relative;
   display: flex;
   justify-content: space-between;
   height: 20vh;
   width: 100vw;
   top: 40%;
   /* left: 0.5rem; */
   z-index: 100;
   font-family: Helvetica, sans-serif;
   font-size: 1.5rem;
}

#logo-center {
   display: none;
}

.mobile-logo {
   display: flex;
   justify-content: center;
   align-items: center;
   font-size: 2rem;
   font-family: Helvetica, sans-serif;
   font-weight: bold;
   width: 1.5rem;

}

#projbtn {
   align-self: center;
}

.nav-button-v {
   font-size: 1.5rem;
}

.openPress {
   -webkit-transform: translate3d(100vw, 0, 0);
   transform: translate3d(100vw, 0, 0);
   transition: transform 1s;
}

.openAbout {
   -webkit-transform: translate3d(-100vw, 0, 0);
   transform: translate3d(-100vw, 0, 0);
   transition: transform 1s;
}

/* press page */

.press-container {
   width: 100vw;
}

.img-grid {
   margin-top: 6vh;
   margin-left: -30vw;
   padding: 1rem;
}

.press-info {
   width: 70vw;
   height: 47vh;
}

.fixed-wrapper {
   left: 173vw;
   height: 20vh;
}

.contact-wrapper {
   height: 20vh;
}

.back_home {
   display: block;
   position: fixed;
   z-index: 2;
   font-family: Helvetica, sans-serif;
   font-size: 1.5rem;
   color: black;
   background-color: white;
   text-transform: uppercase;
   font-weight: bold;
}

.press__mobile {
   margin-left: 75vw;
   margin-top: 90vh;
}

.fixed-wrapper {
   top: 5vh;
}

.contactbtn {
   float: left;
   font-size: 1.4rem;
}

.contact-wrapper ul {
   background-color: rgba(255, 255, 255, 0.829);
   color: black;
   margin-top: 3vh;
   width: 60vw;
   height: 18vh;
   margin-left: -45vw;
   text-align: center;
   justify-content: flex-start;
   padding: 1rem;
   pointer-events: none;
}

.contact-wrapper a {
   color: white;
}

/* about page */
.about-container {
   width: 100vw;
   left: -100vw;

}

Solution

this line of code is invalid:

<link rel='stylesheet' media='only screen and (min-device-width:320px) and (max-device-width: 850px) and (-webkit-device-pixel-ratio: 3) and (-webkit-device-pixel-ratio: 2)' href='css/mobile.css' />

you should add your media queries inside a css file ( probably inside your mobile.css )

@media only screen and (min-width: 320px) {
  .class{
    background-color: green;
  }
}