FWIW the css template is just some bootstrap stuff, and this for the syntax highlighter in the code snippets: /* http://prismjs.com/download.html?themes=prism-twilight&langu... / /* * prism.js Twilight theme * Based (more or less) on the Twilight theme originally of Textmate fame. * @author Remy Bach */

If someone really cares to investigate, the Letsencrypt.org website (Hugo based) is here for starting with:

https://github.com/letsencrypt/website