dark mode 😎 (#112)

* prepare dark mode stuffs

* themed all global colors

* store preference in local storage

* toggle styling

* lightbulb position

* minify bundled script with uglify-js instead of hugo

* detect whether user has an OS-wide dark mode preference and use that by default

* two different colors for each homepage link

* inline bulb SVGs into stylesheet

* fingerprint and cache styles for a year

* fix lightbulb positioning with weird magic numbers, will come back to that

* themed syntax highlighting

* use terser instead of uglify-js (b/c of ES6)

assets/sass/pages/_list.scss

@@ -30,9 +30,12 @@ main#list {
       margin-bottom: 1em;
 
       div.date {
-        color: $color-medium;
         width: 5.25em;
         flex-shrink: 0;
+
+        @include themed() {
+          color: t(color-medium);
+        }
       }
 
       &:last-child {
@@ -42,7 +45,6 @@ main#list {
   }
 }
 
-
 // Responsive
 @mixin responsive--list() {
   main#list {