chore(style): enhance not-prose elements styling (#163)

* chore(css): improve not-prose tags styling

* fix: typo

* chore(style): improve appearance in prose

* feat: support icon in callout shortcode

* chore: add RSS badge to blog list page

* chore: run build:css

* chore: run build:css

* chore: remove unused CSS

* chore: add footer.enable explicitly to config

* chore: use `where` pseudo class for more prose elements

* chore: run build:css

* chore: remove blank space

* chore: rebuild css

* chore: update figure css

exampleSite/content/blog/_index.md

@@ -1,3 +1,10 @@
 ---
 title: "Blog"
 ---
+
+<div style="text-align: center; margin-top: 1em;">
+{{< hextra/hero-badge link="index.xml" >}}
+  <span>RSS Feed</span>
+  {{< icon name="rss" attributes="height=14" >}}
+{{< /hextra/hero-badge >}}
+</div>