--- a/devtools/client/themes/fonts.css
+++ b/devtools/client/themes/fonts.css
@@ -30,17 +30,17 @@
 
 #font-showall {
   border-radius: 0;
   border: 1px solid black;
   margin: 3px;
   cursor: pointer;
   position: absolute;
   bottom: 0;
-  right: 0;
+  offset-inline-end: 0;
 }
 
 .dim > #font-container,
 .font:not(.has-code) .font-css-code,
 .font-is-local,
 .font-is-remote,
 .font.is-local .font-format-url,
 #font-template {