All of the left-navigation theme has been deleted except for the README and the atlassian-plugins.xml file. So if someone builds the theme, it doesn't do anything.

We should either delete the whole thing, or re-instate it.

If we re-instate it, there's a bug where the blog calendar will display: we need to add the following to the theme's CSS file

.whatever-the-class-of-the-blog-calendar-table-is {
display: none;
}