added back content_block headerButtonGroup due to backwards compatibility and modified header.html.ep to fit changes
diff --git a/dev/scss/base/buttongroup.scss b/dev/scss/base/buttongroup.scss
index 1937e53..01e2246 100644
--- a/dev/scss/base/buttongroup.scss
+++ b/dev/scss/base/buttongroup.scss
@@ -110,6 +110,7 @@
 
       &.minimize::after {
 	      content: $fa-minimize;
+        color: $dark-grey;
       }
       
       &.plugin::after {