diff --git a/core/modules/navigation/components/toolbar-button/toolbar-button.css b/core/modules/navigation/components/toolbar-button/toolbar-button.css
index 537305512052895f0bc4c18b6b3a4e93e3308145..3af3cbfdd39d2eb85a18b1ea8a85e69056c836ae 100644
--- a/core/modules/navigation/components/toolbar-button/toolbar-button.css
+++ b/core/modules/navigation/components/toolbar-button/toolbar-button.css
@@ -107,7 +107,7 @@
 }
 [class*="toolbar-button--icon"]:not(:has(.toolbar-button__icon))::before {
   flex-shrink: 0;
-  content: attr(data-icon-text);
+  content: attr(data-icon-text) / "";
   text-align: center;
   color: currentColor;
   font-size: calc(0.75 * var(--admin-toolbar-rem));
diff --git a/core/modules/navigation/components/toolbar-button/toolbar-button.pcss.css b/core/modules/navigation/components/toolbar-button/toolbar-button.pcss.css
index 7e563bc6197b7d163c2d5769f5c917fdcd6e1d6b..9b40b8fcb4601dca2f85b7954513531d5ed825ad 100644
--- a/core/modules/navigation/components/toolbar-button/toolbar-button.pcss.css
+++ b/core/modules/navigation/components/toolbar-button/toolbar-button.pcss.css
@@ -119,7 +119,7 @@
 [class*="toolbar-button--icon"]:not(:has(.toolbar-button__icon)) {
   &::before {
     flex-shrink: 0;
-    content: attr(data-icon-text);
+    content: attr(data-icon-text) / "";
     text-align: center;
     color: currentColor;
     font-size: calc(0.75 * var(--admin-toolbar-rem));
diff --git a/core/scripts/css/compile.js b/core/scripts/css/compile.js
index 5c9426747e8562193bec8a50fb26212b9dcc08ef..9f5b71cb929dcf6375709ac2feba97bfca608953 100644
--- a/core/scripts/css/compile.js
+++ b/core/scripts/css/compile.js
@@ -33,6 +33,7 @@ module.exports = (filePath, callback) => {
           'has-pseudo-class': false,
           'image-set-function': false,
           'prefers-color-scheme-query': false,
+          'content-alt-text': false,
         }
       }),
       postcssPixelsToRem({