Understanding Retina device CSS Media queries

Question

I am working on a WordPress theme and am trying to incorporate retina enabled CSS queries into my CSS file. I would just like to clarify that I have the media queries set up correctly before I change out all my background images. - I have doubled the size of all my background images and perfixed them with the "@2x" naming convention. e.g `icon-user@2x.png`. - I have added a jQuery function into my code to swap out the images with the CSS class of `hires`. - In my CSS document I have a normal CSS class for a background image. Normal CSS query ``` .side-nav .arrow { background: url(../images/arrow-nav.png) no-repeat top left; width: 5px; height: 8px; display: inline-block; margin-left: 10px } ``` Is this the correct way i would change the .side-nav .arrow class for a retina enabled device? When declaring the background size do I keep the size that of the original smaller image? ``` /* All Retina Ready devices larger than 1.5 pixel ratio */ @media only screen and (-moz-min-device-pixel-r…

Accepted Answer

As long as there is some form of scaling taking place, like when you declare

`<meta name="viewport" content="width=...">` (for android/ios/blackberry/WP8)

or

`@ms-viewport {width: ... ;}` (for non-WP8 IE10)

or ... even if you declare nothing most mobile devices will by default automatically scale such that viewport width=980px

then all CSS dimensions you declare with 'px' will exist in the same proportion to their viewport regardless of differences between their physical DPI/PPI

this means you shouldn't have to change a single thing about your style class except the background image's URL when the media query matches a high res device:

```
@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),
only screen and (min-resolution: 144dpi) {
    .side-nav .arrow { 
         background-image:url(../images/arrow-nav@2x.png);
     }
}
```

Understanding Retina device CSS Media queries

Solution

Problem