I received this email from Safari Books Online:
The email is written in English, but notice how the text is aligned unusually to the right. Notice also that the punctuation marks appear at the wrong end of the sentence. I used Firefox developer tools to apply the correct direction, and saw it correctly:
This happens because I use GMail with the Hebrew interface. GMail has to guess the direction of the emails that I receive, because in plain text there’s no easy way to specify the direction (I hope to discuss it in a separate post soon). Usually GMail guesses correctly. Ironically, for HTML-formatted emails like this one, GMail often guesses incorrectly, even though in HTML, unlike in plain text, it’s quite easy to specify the direction by simply adding dir=”ltr” to the root element of the email.
Unfortunately a lot of HTML authors don’t bother to specify explicit direction. Many are not even aware of this exotic dir attribute. Others think that because “ltr” is the default, they don’t have to specify it. They are wrong: As this email shows, the left-to-right HTML content is embedded in a right-to-left environment, and the “rtl” definition propagates to the embedded content.
You could blame GMail, of course, but it’s much more practical to always define the direction of your HTML content, even if it’s the default. You can never know where will your content end up.
P.S.: I read this post before publishing and suddenly realized that its style is quite similar to “Best Practices” books, such as Damian Conway’s classic “Perl Best Practices” – it tells you to do something that is not obviously needed, and explains why it is needed nevertheless. I like to acknowledge sources of inspiration. Thank you, Damian.