CSS for high-resolution images on mobile and retina displays - html

Question

My website images look blurry for users with retina displays. (For example, on the Retina MacBook Pro).
How do I serve high-resolution images to visitors with retina displays, but standard-sized images to everyone else, while keeping the image the same apparent size?

Answer 1

In your HTML, create a <div> like so:
<div class="ninjas-image"></div>
And in your CSS, add:
.ninjas-image {
background-image: url('ninja-devices.png');
width: 410px;
height: 450px;
}
#media (-webkit-min-device-pixel-ratio: 1.5), (min-resolution: 144dpi) {
.ninjas-image {
background-image: url('ninja-devices#2x.png');
background-size: 410px 450px;
}
}
The magic here is in the CSS #media query. We have a double-sized image (ninja-devices#2x.png) that we sub-in when the device reports a ‘device pixel ratio’ of 1.5 (144 dpi) or more. Doing it this way allows you to save on bandwidth by delivering the original, smaller image to non-retina devices, and of course it looks great on retina devices.
Note:
This answer was updated in 2016 to reflect best-practice. min-device-pixel-ratio did not make it in to the standard. Instead, min-resolution was added to the standard, but desktop and mobile Safari don't support it at the time of writing, (thus the -webkit-min-device-pixel-ratio fallback). You can check the latest information at: http://caniuse.com/#feat=css-media-resolution.

Answer 2

We've been using the following to handle multiple cases where the ratio is 1.5 or higher - this takes more devices and browsers into account:
#media only screen and (-webkit-min-device-pixel-ratio: 1.5),
only screen and (-o-min-device-pixel-ratio: 3/2),
only screen and (min--moz-device-pixel-ratio: 1.5),
only screen and (min-device-pixel-ratio: 1.5) {
We have our entire site Retina enabled: http://www.embraceware.com/