how to render heading anchors statically

[jcmf]

The README claims "zero-Javascript output" and "content is exclusively pre-rendered" -- but that doesn't seem to be true of the little # anchors that show up next to headings, for example. I was surprised to discover that those are being rendered using client side Javascript belonging to a third-party zachleat/heading-anchors web component, after the page loads. If I wanted to render those statically, instead of relying on client-side JS to render them, how might I go about it?