Index: chrome/browser/resources/signin/signin_shared.css
--- chrome/browser/resources/signin/signin_shared.css.orig
+++ chrome/browser/resources/signin/signin_shared.css
@@ -39,7 +39,7 @@ a {
   justify-content: flex-end;
 </if>
   padding: var(--action-container-padding);
-<if expr="is_macosx or is_linux or is_chromeos">
+<if expr="is_macosx or is_posix or is_chromeos">
   flex-flow: row-reverse;
   justify-content: flex-start;
 </if>
