text muted AA wcag test improvement

scss/_variables.scss

@@ -51,8 +51,8 @@ $white: #ffffff !default;
 $body-bg: $light !default;
 $body-color: $dark !default;
 
-$text-muted: mix($body-color, #fff, 64%) !default;
-$border-color: rgba(mix($body-color, #fff, 64%), .24) !default;
+$text-muted: mix($body-color, #fff, 68%) !default;
+$border-color: rgba(mix($body-color, #fff, 68%), .24) !default;
 
 $hover-bg: $light-white !default;
 $active-bg: rgba($blue, .06) !default;