Optimize generated HTML size by adding on-the-fly elements

The main focus was the Table of contents rendering, which had a lot of redundant stuff. Headers were the next largest gain.

The main techniques used to reduce size were:

auto-generate a few elements on-the-fly with JavaScript for on-hover effects, but only if it doesn't affect SEO and readability when JS is turned off
use a lot more CSS ::after and ::before to avoid embedding repetitive icons multiple times on the HTML

After this changes, the rendered size of cirosantilli.com fell from 216 MiB to 156.5 MiB, which is kind of cool!

 Ancestors