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)

.stylelintrc

@@ -6,7 +6,7 @@
     "function-parentheses-space-inside": null,
     "function-url-quotes": null,
     "indentation": [ 2, { "severity": "warning" } ],
-    "max-nesting-depth": 5,
+    "max-nesting-depth": 6,
     "number-no-trailing-zeros": null,
     "order/properties-alphabetical-order": null,
     "rule-empty-line-before": null,