diff --git a/toolkit/themes/shared/tree.inc.css b/toolkit/themes/shared/tree.inc.css
index acfff53caf63..d2802c47ab89 100644
--- a/toolkit/themes/shared/tree.inc.css
+++ b/toolkit/themes/shared/tree.inc.css
@@ -200,6 +200,7 @@ html|input.tree-input {
   margin: 0;
   margin-inline-start: -4px;
   padding: 1px;
+  font: inherit;
 }
 
 .scrollbar-topmost {