🌓 Adds Dark Mode (#210)

* feat(dark mode): set up first set of colors

* feat(dark mode): define state colours

* 🧹

* feat(dark mode): variablify all teh wordz

* feat(dark mode): set colors on body

* feat(dark mode): replace hard coded color value

* feat(dark mode): 🌑

* feat(a11y): update link focus styles

- restores visible focus in windows high contrast mode
- increases visibility in boxes with bg colour

* feat(dark mode): enable postcss

* 💅

* feat(dark mode): add user control

* chore: use generic headline name

* feat(dark mode): hide switch until script loads

* feat(dark mode): increase link contrast

* add content warning to footer nav partial

* feat(dark mode): replace hard coded colour value in alertbox

* feat(dark mode): tone down text colour

* feat(dark mode): properly invert code elements

* 🧹 move box styles into own partial

* feat(dark mode): use darker colour as background for links

.eleventy.js

@@ -198,6 +198,8 @@ module.exports = function(config) {
 
   config.setLibrary('md', mdIt);
 
+  config.addPassthroughCopy({ [`./11ty/assets/js/**/*`]: '/js' });
+
   // You can return your Config object (optional).
   return {
     dir: {