Index: wp-admin/css/media.dev.css
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/css/media.dev.css	(revision 21421)
+++ wp-admin/css/media.dev.css	(revision )
@@ -327,3 +327,32 @@
 table.not-image tr.image-only {
 	display: none;
 }
+
+/**
+ * HiDPI Media Queries
+ */
+@media
+only screen and (-webkit-min-device-pixel-ratio: 1.5),
+only screen and (min-device-pixel-ratio: 1.5) {
+
+	.image-align-none-label {
+		background-image: url(../images/align-none-2x.png);
+		background-size: 21px auto;
+	}
+
+	.image-align-left-label {
+		background-image: url(../images/align-left-2x.png);
+		background-size: 21px auto;
+	}
+
+	.image-align-center-label {
+		background-image: url(../images/align-center-2x.png);
+		background-size: 21px auto;
+	}
+
+	.image-align-right-label {
+		background-image: url(../images/align-right-2x.png);
+		background-size: 21px auto;
+	}
+
+}
\ No newline at end of file