diff --git a/browser/base/content/tabbrowser.css b/browser/base/content/tabbrowser.css
index b873bd3bbb17..b4b849991f59 100644
--- a/browser/base/content/tabbrowser.css
+++ b/browser/base/content/tabbrowser.css
@@ -38,7 +38,7 @@
 .tab-icon-overlay:is([soundplaying], [muted], [activemedia-blocked], [pictureinpicture], [crashed]) {
   display: revert;
 }
-} /* end proton */
+} /*** END proton ***/
 
 @supports not -moz-bool-pref("browser.proton.tabs.enabled") {
 .tab-icon-sound:not([activemedia-blocked]) > .tab-icon-sound-blocked-label,
@@ -60,7 +60,7 @@
 .tab-icon-overlay[crashed] {
   display: -moz-box;
 }
-} /* end !proton */
+} /*** END !proton ***/
 
 .tab-label {
   white-space: nowrap;
diff --git a/browser/themes/osx/browser.css b/browser/themes/osx/browser.css
index 1c11c0d1dbf7..0a7e2d0cbc5f 100644
--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -53,7 +53,7 @@
 #navigator-toolbox:not(:-moz-lwtheme) {
   background-color: #f0f0f4;
 }
-} /* END proton */
+} /*** END proton ***/
 
 #navigator-toolbox:not(:-moz-lwtheme):-moz-window-inactive {
   --tabs-border-color: rgba(0,0,0,.05);