The website is built on Jekyll, and makes use of gulp as its task runner. Prism is used for syntax highlighting.
Update (27 April 2020): after a good 1992 days (if I had waited a week, it would have been 2000 days, oh well), this Jekyll version of the site hosted on GitHub Pages will be retired but still up for posterity's sake. Source code for "new" version which looks almost exactly the same here (still served at the same URL chenhuijing.com). You're not supposed to SEE the difference.