The <article> tag is for self-contained content, which the post list isn't really. I hope that this change makes search engines display the blog's introduction instead of the first post's introduction in their results.
This ToC is only shown when the screen is too small for the sticky sidebar ToC.
We use a `<!-- toc -->` comment and the `replace` function to allow inserting the ToC at well defined points of the page. We don't use the shortcode feature of Zola because of https://github.com/getzola/zola/issues/584.
