Clean up CSS

- Add vim folds to make organized sections
- Rename a lot of classes from post- to page-
- Generalize series CSS classes better
- Clean up navbar div structure
- Remove langpicker and most of multilingual support
- many other minor tweaks

layouts/partials/page-metadata/item/authors.html

@@ -0,0 +1,16 @@
+{{ with .Params.authors }}
+    <span class="page-metadata-item" aria-label="{{ i18n "aria_post_meta_authors" }}">
+        {{ partial "icon.html" "user-circle" }}
+
+        {{ if index $.Site.Taxonomies "authors" }}
+            {{ $authors := slice }}
+            {{ range . }}
+                {{ $url := (printf "authors/%s" (. | anchorize)) | absLangURL }}
+                {{ $authors = $authors | append (printf `<a href="%s">%s</a>` $url . | safeHTML) }}
+            {{ end }}
+            {{ delimit $authors ", " }}
+        {{ else }}
+            {{ delimit . ", " }}
+        {{ end }}
+    </span>
+{{ end }}