fix functions, lighter colors on active

scss/mixins/_buttons.scss

@@ -3,14 +3,14 @@
 // Easily pump out default styles, as well as :hover, :focus, :active,
 // and disabled options for all buttons
 
-@mixin button-variant($background, $border, $hover-background: darken($background, 7.5%), $hover-border: darken($border, 10%), $active-background: darken($background, 12.5%), $active-border: darken($border, 15%)) {
-  @include color-yiq($background);
+@mixin button-variant($background, $border, $hover-background: darken($background, 7.5%), $hover-border: darken($border, 10%), $active-background: darken($background, 10%), $active-border: darken($border, 12.5%)) {
+  color: color-yiq($background);
   background-color: $background;
   border-color: $border;
   @include box-shadow($btn-box-shadow);
 
   @include hover {
-    @include color-yiq($hover-background);
+    color: color-yiq($hover-background);
     background-color: $hover-background;
     border-color: $hover-border;
   }