Index: src/wp-content/themes/twentytwelve/css/blocks.css
===================================================================
--- src/wp-content/themes/twentytwelve/css/blocks.css	(revision 58876)
+++ src/wp-content/themes/twentytwelve/css/blocks.css	(working copy)
@@ -263,6 +263,11 @@
 	color: #7c7c7c;
 }
 
+.is-style-outline .wp-block-button__link,
+.is-style-outline .wp-block-button__link:visited {
+	color: currentColor;
+}
+
 .wp-block-button.is-style-outline .wp-block-button__link,
 .wp-block-button.is-style-outline .wp-block-button__link:visited {
 	background-color: inherit;