@mixin respond-to($min-width, $max-width: false) {
  @if $responsive {
    @media screen and (min-width: $min-width) {
      @if $max-width {
        @media (max-width: $max-width) {
          @content
        }
      } @else {
        @content;
      }
    }
  } @else if $min-width <= $mq-l and (not $max-width or $max-width and $max-width >= $mq-l) {
    @content;
  }
}

@mixin respond-to($min-width, $max-width: false) {
  @if $responsive {
    @media screen and (min-width: $min-width) {
      @if $max-width {
        @media (max-width: $max-width) {
          @content
        }
      } @else {
        @content;
      }
    }
  } @else if $min-width <= $mq-l and (not $max-width or $max-width and $max-width >= $mq-l) {
    @content;
  }
}

@mixin device-pixel-ratio($ratio: 2) {
  @media only screen and (-webkit-min-device-pixel-ratio: $ratio),
  only screen and (min--moz-device-pixel-ratio: $ratio),
  only screen and (-o-min-device-pixel-ratio: #{($ratio*10)}/10),
  only screen and (min-device-pixel-ratio: $ratio),
  only screen and (min-resolution: #{($ratio*96)}dpi),
  only screen and (min-resolution: #{$ratio}dppx) {
    @content;
  }
}

Add pixel device width mixin to lib
Add pixel device width mixin to lib
