Set dark theme as default to prevent flicker

Defaulting to the dark theme prevents flickering during page transitions. This also helps avoid flicker even when users switch to the light theme manually.

Author: mooreryan

_quarto.yml

@@ -89,10 +89,10 @@ bibliography: references.bib
 format:
   html:
     theme:
-      light: [custom.scss, flatly]
       dark: [custom.scss, darkly]
+      light: [custom.scss, flatly]
       # - custom.scss
-      # - cosmo
+      # - flatly
     include-after-body:
       - includes/switch_images_for_theme.html
       - includes/simple_analytics.html