less corny header and note meta icons (#746)

* less corny header and note meta icons

* swap out more twemojis

* indicate active page in nav bar

* update favicons

* extract `<MenuLink />` into its own component

* change hover effect to an underline

* cropped header photo

styles/colors.css

@@ -14,6 +14,7 @@
   --link-underline: rgba(14, 109, 194, 0.4);
   --success: #44a248;
   --error: #ff1b1b;
+  --warning: #f78200;
 
   /* Syntax Highlighting (light) - modified from Monokai Light: https://github.com/mlgill/pygments-style-monokailight */
   --code-text: #313131;
@@ -45,6 +46,7 @@
   --link-underline: rgba(136, 199, 255, 0.4);
   --success: #78df55;
   --error: #ff5151;
+  --warning: #f2b702;
 
   /* Syntax Highlighting (dark) - modified from Dracula: https://github.com/dracula/pygments */
   --code-text: #e4e4e4;