CSS @media queries for high-res displays not working

Question

I've set up a bit of CSS to detect whether the client's using a Retina or other HiDPI display, and display a different background-image for various divs based on that. Here's my syntax:

<!-- LoDPI and MedDPI displays -->
#div {
    opacity:0.4;
    position:absolute;
    top:0px;
    z-index:2;
    width:1600px;
    height:900px;
    animation-name:ring;
    animation-delay:0s;
    animation-duration:1500ms;
    animation-timing-function:cubic-bezier(0.225, 1.650, 0.000, 0.805);
    animation-fill-mode:forwards;
    background-image:url(/valid/path/to/regular/file);
}

<!-- For Retina and HiDPI displays -->
@media only screen and (min-device-pixel-ratio: 1.4) {
#div {
    background-image:url(/valid/link/to/HiDPI/file);
    background-position:center;
    background-size:contain;
    }
}

The problem is, when I try this out on my Retina MBP, whose pixel ratio is set to 1.5 ("acts like 1920x1200), displays the normal-res images rather than the high-res ones.

Answer 1

You don't have all your curly braces closed. Regardless, for better support matrix, substitute your media query with

@media only screen and (-moz-min-device-pixel-ratio: 1.5),
       only screen and (-o-min-device-pixel-ratio: 3/2),
       only screen and (-webkit-min-device-pixel-ratio: 1.5),
       only screen and (min-device-pixel-ratio: 1.5) {
         /*your rules*/
       }