Nesting Media Queries

问题

By default I want to give my body element a green border. On a device that supports retina display I want to check for size first. On an ipad I want to give my body a red border and on an iphone I want to give it a blue border. But nesting media queries like so doesn't work:

body { border: 1px solid green; }

@media (-webkit-min-device-pixel-ratio: 2), (min-resolution: 192dpi) { 
   @media (max-width: 768px) and (min-width: 320px) {
      body { border: 1px solid red; }
   }
   @media (max-width: 320px) {
      body { border: 1px solid blue; }
   }
}

回答1:

No. You need to use the and operator and write that as two queries. You can, however, do this in SCSS, which will compile to CSS, but it will combine them by unfolding them and using the and operator.

This is a common problem, and once I first wrote LESS or SCSS, I didn't ever want to go back to writing this long-hand.

Long-handed CSS:

@media (-webkit-min-device-pixel-ratio: 2) and (max-width: 768px) and (min-width: 320px),
                  (min-resolution: 192dpi) and (max-width: 768px) and (min-width: 320px) {
  body {
    border: 1px solid red;
  }
}
@media (-webkit-min-device-pixel-ratio: 2) and (max-width: 320px),
                  (min-resolution: 192dpi) and (max-width: 320px) {
  body {
    border: 1px solid blue;
  }
}

Nesting queries may work, but support varies across browsers.

来源：https://stackoverflow.com/questions/16114000/nesting-media-queries