apply same active/focus shadow styling to button variants

scss/mixins/_buttons.scss

@@ -42,6 +42,7 @@
     }
     border-color: $active-border;
 
+    &:focus {
       // Avoid using mixin so we can pass custom focus shadow properly
       @if $enable-shadows {
         box-shadow: $btn-active-box-shadow, 0 0 0 $btn-focus-width rgba($border, .5);
@@ -49,6 +50,7 @@
         box-shadow: 0 0 0 $btn-focus-width rgba($border, .5);
       }
     }
+  }
 }
 
 @mixin button-outline-variant($color, $color-hover: #fff, $active-background: $color, $active-border: $color) {