Deprecate respond-to mixin, Zen uses css @media directly instead.

assets/sass/base/forms/_forms.scss

@@ -99,7 +99,7 @@ textarea {
 }
 
 // For forms on mobile with single field add space between it and the submit button.
-@include respond-to(s) {
+@media (min-width: 666px) {
   input:only-of-type {
     &:has(+ [type='submit']) {
       margin-inline-end: .5rem;

assets/sass/base/images/_images.scss

@@ -5,7 +5,7 @@ img {
   &.image {
     --image-padding: .75rem;
 
-    @include respond-to(s) {
+    @media (min-width: 666px) {
       &.center {
         margin-inline: auto;
       }
@@ -41,7 +41,7 @@ figure {
       // Nicer text wrap, e.g. no lone word on last line.
       text-wrap: pretty;
 
-      @include respond-to(s) {
+      @media (min-width: 666px) {
         display: table-caption;
         caption-side: bottom;
         padding-block-start: 0;
@@ -52,7 +52,7 @@ figure {
       }
     }
 
-    @include respond-to(s) {
+    @media (min-width: 666px) {
       display: table;
 
       &.left {

assets/sass/base/reset/_reset.scss

@@ -78,7 +78,7 @@ select {
 }
 
 [type='search'] {
-  @include respond-to(s) {
+  @media (min-width: 666px) {
     // Correct the odd appearance in Safari on desktop.
     -webkit-appearance: textfield;
   }