ducha-qianduan/public/assets/libs/bootstrap/less/mixins/image.less

// stylelint-disable media-feature-name-no-vendor-prefix, media-feature-parentheses-space-inside, media-feature-name-no-unknown, indentation, at-rule-name-space-after

// Responsive image
//
// Keep images from scaling beyond the width of their parents.
.img-responsive(@display: block) {
  display: @display;
  max-width: 100%; // Part 1: Set a maximum relative to the parent
  height: auto; // Part 2: Scale the height according to the width, otherwise you get stretching
}


// Retina image
//
// Short retina mixin for setting background-image and -size. Note that the
// spelling of `min--moz-device-pixel-ratio` is intentional.
.img-retina(@file-1x; @file-2x; @width-1x; @height-1x) {
  background-image: url("@{file-1x}");

  @media
  only screen and (-webkit-min-device-pixel-ratio: 2),
  only screen and ( min--moz-device-pixel-ratio: 2),
  only screen and ( -o-min-device-pixel-ratio: 2/1),
  only screen and ( min-device-pixel-ratio: 2),
  only screen and ( min-resolution: 192dpi),
  only screen and ( min-resolution: 2dppx) {
    background-image: url("@{file-2x}");
    background-size: @width-1x @height-1x;
  }
}