Advanced media query considerations
The following section deals with concerns for when you are highly proficient in writing media queries. Think of these topics as micro-optimizations. If you are just starting with media queries, you certainly shouldn't be worrying about any of these topics yet. Jump on to the Media Queries Level 4 section instead!
OK, media query uber-geekery, here we go...
Organizing media queries
Ordinarily, for a browser, CSS is considered to be a render-blocking asset. The browser needs to fetch and parse a linked CSS file before the rendering of the page can complete. This stands to reason as the browser needs to know what styles to apply for laying out and painting the page.
However, modern browsers are smart enough to discern which style sheets, (linked with media queries in the head) need to be analyzed immediately and which can be deferred until after the initial page rendering. The upshot of this is that for these browsers, CSS files...
