Fix overlay mixin. Remove rtl mixin.

assets/sass/_init.scss

@@ -14,5 +14,5 @@
 @import 'mixins/clearfix/clearfix';
 @import 'mixins/debug/debug';
 @import 'mixins/flex-calc/flex-calc';
-@import 'mixins/rtl/rtl';
+@import 'mixins/overlay/overlay';
 @import 'mixins/spacing/spacing';

assets/sass/_variables.scss

@@ -169,8 +169,5 @@ $gutters-reverse:     calc(0px - (5px + 1.5625vw));
 // Use like this: var(--indent-amount)
 $indent-amount:       2rem;
 
-// Control whether RTL styles are added.
-$include-rtl: false;
-
 // Show horizontal grid to help with debugging typography.
 $debug: false;

assets/sass/mixins/overlay/_overlay.scss

@@ -1,5 +1,5 @@
-@mixin overlay($opacity: '0.5', $color: $nearblack, $color2: $grey-light) {
-  --color-overlay: $color;
-  --color-overlay2: $color2;
-  border-image: linear-gradient(rgba(var(--color-overlay) / $opacity), rgba(var(--color-overlay2) / $opacity)) fill 1;
+@mixin overlay() {
+  --color-overlay: var(--color-black-20);
+  --color-overlay2: var(--color-black-10);
+  border-image: linear-gradient(var(--color-overlay), var(--color-overlay2)) fill 1;
 }

assets/sass/mixins/rtl/_rtl.scss

@@ -1,26 +0,0 @@
-// stylelint-disable scss/at-if-closing-brace-newline-after, scss/at-if-closing-brace-space-after
-
-$include-rtl: true !default;
-
-// rtl()
-//
-// Includes Right-To-Left language support by adding a selector of
-// `[dir="rtl"]`.
-//
-// Can be turned off globally by setting `$include-rtl: false;`.
-//
-// $selector = ':dir(rtl)' - The RTL selector.
-@mixin rtl($selector: ':dir(rtl)') {
-  @if $include-rtl {
-    @if & {
-      &#{$selector} {
-        @content;
-      }
-    }
-    @else {
-      #{$selector} {
-        @content;
-      }
-    }
-  }
-}