Optimizing CSS by removing unused media queries. One of the core ideas is that you can use the media attribute when including your stylesheets like so:
<link href="print.css" rel="stylesheet" media="print">
<link href="mobile.css" rel="stylesheet" media="screen and (max-width: 600px)">In the article, Dario links to resolution) can change when a user with a multi-screen setup moves a window from say a Retina laptop screen to a bigger desktop monitor, or the user can unplug their media features instead (see the text under the edit this page on GitHub.