diff --git a/css/leptonContent.css b/css/leptonContent.css
index 72ea6ee..7e5a57a 100644
--- a/css/leptonContent.css
+++ b/css/leptonContent.css
@@ -46,6 +46,11 @@
     padding-inline-end: 1px !important; /* Original: 4px */
   }
 }
+@-moz-document url-prefix("about:policies") {
+  #categories > .category {
+    box-sizing: border-box;
+  }
+}
 /** Video player **************************************************************/
 /* Control Bar Size */
 @supports -moz-bool-pref("userContent.player.size") {
@@ -3713,6 +3718,11 @@
     padding-inline-end: 1px !important; /* Original: 4px */
   }
 }
+@-moz-document url-prefix("about:policies") {
+  #categories > .category {
+    box-sizing: border-box;
+  }
+}
 /** Video player **************************************************************/
 /* Control Bar Size */
 @media (-moz-bool-pref: "userContent.player.size") {
diff --git a/css/leptonContentESR.css b/css/leptonContentESR.css
index b4ee702..40ab7f0 100644
--- a/css/leptonContentESR.css
+++ b/css/leptonContentESR.css
@@ -46,6 +46,11 @@
     padding-inline-end: 1px !important; /* Original: 4px */
   }
 }
+@-moz-document url-prefix("about:policies") {
+  #categories > .category {
+    box-sizing: border-box;
+  }
+}
 /** Video player **************************************************************/
 /* Control Bar Size */
 @supports -moz-bool-pref("userContent.player.size") {
diff --git a/src/contents/_compatibility.scss b/src/contents/_compatibility.scss
index 121880c..3a205d2 100644
--- a/src/contents/_compatibility.scss
+++ b/src/contents/_compatibility.scss
@@ -56,3 +56,10 @@
     padding-inline-end: 1px !important; /* Original: 4px */
   }
 }
+
+@include moz-document(url-prefix "about:policies") {
+  // #923
+  #categories > .category {
+    box-sizing: border-box;
+  }
+}