Added this changelog (using the method detailed in this post by ten).
After some quick and dirty fixes this morning, the website has finally caught up on the major Eleventy update last year. It now runs on Eleventy v3. I messed up the RSS feed during the process but it should be all good now. The site has also reached a stage where I no longer feel the need to keep tweaking every tiny detail of the CSS ad nauseam—I'm finally happy with how it looks.
Happy new year.