Website: Text, especially headers, look slightly pixelated

The font used seems to be _Roboto_.

I notice it in Firefox 106.0.2 and Chromium on Ubuntu 20.04 . It looks good on Android.

Other people complain about the same:

* https://medium.com/@kasperpeulen/why-the-roboto-font-sometimes-look-painfully-ugly-and-how-to-fix-it-d7cfadb74cf0
* https://stackoverflow.com/questions/31011278/roboto-from-materializecss-weird-font-rendering-in-chrome-firefox-ok-with-ie
* https://stackoverflow.com/questions/34751547/display-issues-with-roboto-font-from-materialize-in-firefox/36803177#36803177

I reported this upstream in the hugo-book theme: https://github.com/alex-shpak/hugo-book/issues/498