Better slug in sidenote and header image option in post

src/_includes/section.liquid

@@ -0,0 +1,2 @@
+</section>
+<section>

src/_includes/sidenote.liquid

@@ -1,3 +1,3 @@
-{% assign sn_slug = sidenote | strip | strip_html | slice: 0, 50 | downcase | replace: '.', '' |replace: ' ', '-' %}{% capture snid %}sn-{{ sn_slug}}{% endcapture %}<label for="{{ snid }}" class="margin-toggle sidenote-number"></label>
+{% assign sn_slug = sidenote | strip | strip_html | strip_newlines | slice: 0, 50 | downcase | remove: '"' | remove: "'" | remove: ' ' | remove: '.' | remove: '-' | remove: '_' %}{% capture snid %}sn-{{ sn_slug}}{% endcapture %}<label for="{{ snid }}" class="margin-toggle sidenote-number"></label>
 <input type="checkbox" id="{{ snid }}" class="margin-toggle">
-<span class="sidenote">{{ sidenote }}</span>
+<span class="sidenote">{{ sidenote | strip_newlines }}</span>

src/_layouts/post.liquid

@@ -29,6 +29,12 @@
     
     <article id="main">
       <section>
+        {% if page.data.header_image %}
+          <figure class="fullwidth">
+            <img style="box-shadow: 1px 6px 14px #ba8" src="{{page.data.header_image}}">
+          </figure>
+        {% endif %}
+
         {{ page.content }}
       </section>
     </article >

src/index.md

@@ -13,6 +13,12 @@ I publish some public code sometimes
 
  - [git.natronics.org/natronics](https://git.natronics.org/natronics)
 
+
+### Maps
+
+[I made a couple of maps](/maps/)
+
+
 ### Beep Boop
 
 [I made a couple of sounds](/sounds/)

src/maps/index.md

@@ -0,0 +1,21 @@
+---
+title: Maps
+layout: page.liquid
+---
+
+# Maps
+
+I made some maps.
+
+
+## Colorful Pennsylvania 
+
+_July 2021_
+
+<figure class="fullwidth">
+  <a href="colorful_pennsylvania.png" target="_blank" style="text-decoration:none;background:none;text-shadow:none">
+    <img src="colorful_pennsylvania_thumb.jpg">
+  </a>
+</figure>
+
+I chose an unusual, bright color gradient mapped to elevation and rendered topography.