Added site theme switcher

I’ve been trying to carve out some time this week to update my own website, something which I always mean to do but something else always seems more important or more urgent.

The feature I’ve just added was inspired by Léonie Watson’s website, and that’s to have a “dark” mode as well as the default “light” mode.  A simple switch allows the user to choose their preference, and this is remembered for next time using a cookie.

This was fun to build and hopefully will be of some use to people.  I know I certainly prefer to have most things in dark mode, and now my own website will be one of them.