.feed {
  display: inline-block;
  padding: 0 $gutter-one-third 0 $gutter-two-thirds;
  font-weight: bold;
  background: image-url('feed-icon-black.png') 0 40% no-repeat;
}
.govdelivery {
  display: inline-block;
  padding: 0 $gutter-one-third 0 $gutter-two-thirds+$gutter-one-sixth;
  font-weight: bold;
  background: image-url('mail-icon.png') 0 40% no-repeat;
  @include hidpi {
    background-image: image-url('mail-icon-2x.png');
    background-size: $gutter-two-thirds 14px;
  }
}

.feed {
  display: inline-block;
  padding: 0 $gutter-one-third 0 $gutter-two-thirds;
  font-weight: bold;
  background: image-url('feed-icon-black.png') 0 40% no-repeat;
}
.govdelivery {
  display: inline-block;
  padding: 0 $gutter-one-third 0 $gutter-two-thirds+$gutter-one-sixth;
  font-weight: bold;
  background: image-url('mail-icon.png') 0 40% no-repeat;
  @include hidpi {
    background-image: image-url('mail-icon-x2.png');
    background-size: $gutter-two-thirds 14px;
  }
}

Fix email icon not showing on hidpi screens Update hidpi image url as 2x instead of x2
Fix email icon not showing on hidpi screens
Update hidpi image url as 2x instead of x2

https://www.pivotaltracker.com/story/show/48366863
