On Macs double dash will be converted to an em-dash (in some apps?) unless you untick "use smart quotes and dashes". See https://superuser.com/questions/555628/

On Macs double dash will be converted to an em-dash (in some apps?) unless you untick "use smart quotes and dashes". See https://superuser.com/questions/555628/how-to-stop-mac-to-convert-typing-double-dash-to-emdash https://superuser.com/questions/555628/how-to-stop-mac-to-co... I'm on Firefox and it doesn't seem to affect me, but I'm pretty sure I've seen it in Safari.