Index: wp-content/themes/twentytwelve/css/blocks.css
===================================================================
--- wp-content/themes/twentytwelve/css/blocks.css	(revision 55900)
+++ wp-content/themes/twentytwelve/css/blocks.css	(working copy)
@@ -262,7 +262,6 @@
 .entry-content .wp-block-button__link,
 .entry-content .wp-block-button__link:visited {
 	background-color: #e6e6e6;
-	color: #7c7c7c;
 }
 
 .wp-block-button.is-style-outline .wp-block-button__link,