no space or slash between date and byline

When I post an article, the date and byline are displayed with no space between them.
(see https://sashavodnik.com/2015/01/30/getting-started-with-stackexchange-com/)
I see there’s a .entry-meta > .span:before rule that creates a slash with margins, and I don’t understand why it’s not being displayed. When I’m logged in, I do get a slash between the byline and the edit link.
I even manually added a .byline:before rule to replicate the .entry-meta > .span: before rule, but it is not applied.