Mobile: center pinned post, pagination fixes, minor layout tweaks

- First (pinned) post on mobile: title and image centered
- Pagination: restored page counter on mobile, buttons above footer
- Typography and layout minor improvements

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

layouts/shortcodes/figure.html

@@ -27,8 +27,8 @@ NB this overrides Hugo's built-in "figure" shortcode but is backwards compatible
 
 <div class="box{{ with .Get "caption-position" }} fancy-figure caption-position-{{.}}{{end}}{{ with .Get "caption-effect" }} caption-effect-{{.}}{{end}}" {{ with .Get "width" }}style="max-width:{{.}}"{{end}}>
   <figure {{ with .Get "class" }}class="{{.}}"{{ end }} itemprop="associatedMedia" itemscope itemtype="http://schema.org/ImageObject">
-    <div class="img"{{ if .Parent }} style="background-image: url('{{ $thumbURL }}');"{{ end }}{{ with .Get "size" }} data-size="{{.}}"{{ end }}>
-      <img itemprop="thumbnail" src="{{ $thumbURL }}" {{ with .Get "alt" | default (.Get "caption") }}alt="{{.}}"{{ end }}/><!-- <img> hidden if in .gallery -->
+    <div class="img"{{ if .Parent }} data-bg="url('{{ $thumbURL }}')"{{ end }}{{ with .Get "size" }} data-size="{{.}}"{{ end }}>
+      <img itemprop="thumbnail" src="{{ $thumbURL }}" loading="lazy" {{ with .Get "alt" | default (.Get "caption") }}alt="{{.}}"{{ end }}/><!-- <img> hidden if in .gallery -->
     </div>
     {{ with $linkURL }}<a href="{{ . }}" itemprop="contentUrl"></a>{{ end }}
     {{- if or (or (.Get "title") (.Get "caption")) (.Get "attr")}}