This is true whether you say dir=ltr, dir=rtl, or even dir=auto (even though dir=auto is in fact supposed to imply isolation on any element - see https://bugs.webkit.org/show_bug.cgi?id=63903). Please note that <bdi dir="ltr|rtl"> is very useful - IMO, it should replace <span dir="ltr|rtl"> as the usual way of indicating an inline direction change: isolation extremely rarely hurts, and is often quite necessary. This is bad enough, but given that <bdi> currently does not have dir=auto by default (https://bugs.webkit.org/show_bug.cgi?id=68773), <bdi> is currently completely broken. The bug is due to the current default stylesheet, which says that specifying a dir attribute sets unicode-bidi to embed. This is incorrect in HTML5, i.e. http://dev.w3.org/html5/spec/Overview.html#bidirectional-text, which says that the default stylesheet should go like this: :dir(ltr) { direction: ltr; } :dir(rtl) { direction: rtl; } [dir] { unicode-bidi: embed; } bdi, bdi[dir], output, output[dir], [dir=auto i] { unicode-bidi: isolate; } bdo, bdo[dir] { unicode-bidi: bidi-override; } bdo[dir=auto i] { unicode-bidi: bidi-override isolate; } textarea[dir=auto i], pre[dir=auto i] { unicode-bidi: plaintext; } Implementing this trivial fix would also fix https://bugs.webkit.org/show_bug.cgi?id=63903.