Media query not working

// my styles
.style{
  h1{
    color: blue;
  }
}

// media query not working wihtout !important
@media (max-width:900px) {
    h1{
        color: red;
        // color: red !important;
    }
}

// my styles
.style{
  h1{
    color: blue;
  }
}

// media query not working wihtout !important
@media (max-width:900px) {
    h1{
        color: red;
        // color: red !important;
    }
}