diff --git a/browser/themes/linux/browser.css b/browser/themes/linux/browser.css
index f9f33ebde546..6501ed29b1c5 100644
--- a/browser/themes/linux/browser.css
+++ b/browser/themes/linux/browser.css
@@ -270,6 +270,11 @@ notification[value="translation"] menulist > .menulist-dropmarker {
 /* AutoComplete */
 
 %include ../shared/autocomplete.inc.css
+
+#PopupAutoComplete > richlistbox > richlistitem[originaltype~="datalist-first"] {
+  border-top: 1px solid ThreeDShadow;
+}
+
 %include ../shared/urlbar-autocomplete.inc.css
 
 :root {
@@ -277,10 +282,6 @@ notification[value="translation"] menulist > .menulist-dropmarker {
   --urlbar-popup-action-color: -moz-nativehyperlinktext;
 }
 
-#PopupAutoComplete > richlistbox > richlistitem[originaltype~="datalist-first"] {
-  border-top: 1px solid ThreeDShadow;
-}
-
 .urlbarView {
   font-size: 1.05em;
 }
diff --git a/browser/themes/osx/browser.css b/browser/themes/osx/browser.css
index f27991a5e571..a7efe753d19c 100644
--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -282,6 +282,11 @@
 /* ----- AUTOCOMPLETE ----- */
 
 %include ../shared/autocomplete.inc.css
+
+#PopupAutoComplete > richlistbox > richlistitem[originaltype~="datalist-first"] {
+  border-top: 1px solid #C7C7C7;
+}
+
 %include ../shared/urlbar-autocomplete.inc.css
 
 :root {
@@ -289,8 +294,10 @@
   --urlbar-popup-action-color: hsl(178, 100%, 28%);
 }
 
-#PopupAutoComplete > richlistbox > richlistitem[originaltype~="datalist-first"] {
-  border-top: 1px solid #C7C7C7;
+.urlbarView:not(:-moz-lwtheme),
+#PopupSearchAutoComplete:not(:-moz-lwtheme) {
+  /* Set custom disabled text color since native graytext is too faint on macOS 10.14+. */
+  --panel-disabled-color: #737373;
 }
 
 .urlbarView {
diff --git a/browser/themes/windows/browser.css b/browser/themes/windows/browser.css
index 189c1f6e09e3..896710294e0e 100644
--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -572,12 +572,13 @@ menuitem.bookmark-item {
 /* autocomplete */
 
 %include ../shared/autocomplete.inc.css
-%include ../shared/urlbar-autocomplete.inc.css
 
 #PopupAutoComplete > richlistbox > richlistitem[originaltype~="datalist-first"] {
   border-top: 1px solid ThreeDShadow;
 }
 
+%include ../shared/urlbar-autocomplete.inc.css
+
 @media (-moz-windows-default-theme) {
   :root {
     --urlbar-popup-url-color: hsl(210, 77%, 47%);
diff --git a/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js b/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js
index 40165e9ba332..df4e44794b5b 100644
--- a/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js
+++ b/toolkit/components/extensions/test/browser/browser_ext_themes_autocomplete_popup.js
@@ -253,16 +253,19 @@ add_task(async function test_popup_url() {
     "darktext should not be set!"
   );
 
-  // Calculate what GrayText should be. May differ between platforms.
-  let span = document.createXULElement("span");
-  span.style.color = "GrayText";
-  document.documentElement.appendChild(span);
-  let GRAY_TEXT = window.getComputedStyle(span).color;
-  span.remove();
+  // Calculate what GrayText should be. Differs between platforms.
+  // We don't use graytext for urlbar results on Mac as it's too faint.
+  if (AppConstants.platform != "macosx") {
+    let span = document.createXULElement("span");
+    span.style.color = "GrayText";
+    document.documentElement.appendChild(span);
+    let GRAY_TEXT = window.getComputedStyle(span).color;
+    span.remove();
 
-  Assert.equal(
-    window.getComputedStyle(urlResult.element.separator, ":before").color,
-    GRAY_TEXT,
-    `Urlbar popup separator color should be set to ${GRAY_TEXT}`
-  );
+    Assert.equal(
+      window.getComputedStyle(urlResult.element.separator, ":before").color,
+      GRAY_TEXT,
+      `Urlbar popup separator color should be set to ${GRAY_TEXT}`
+    );
+  }
 });