Stylesheet tweaks.

Based on the tweaks I'm using already for SDL Sopwith and wadptr.

pkg/macos/GNUmakefile

@@ -8,7 +8,7 @@ DOC_FILES = README.md COPYING.md
 DMG = wadgadget.dmg
 ICONS = app.icns wadfile.icns
 PANDOC_FLAGS = --embed-resources --resource-path=$(TOPLEVEL) \
-               -s --template=default.html5
+               -s --template=default.html5 -H style.html
 
 $(DMG) : tmp.dmg
 	rm -f $@

pkg/macos/style.html

@@ -0,0 +1,59 @@
+
+<!-- Tweaks to the pandoc output style to make the resulting HTML
+     look much nicer. -->
+
+<style>
+body {
+    background-color: white;
+    margin-top: 1.5em;
+    margin-bottom: 4em;
+
+    max-width: 45em;
+    margin-left: auto;
+    margin-right: auto;
+    box-sizing: border-box;
+
+    padding: 0;
+    padding-left: 1.3em;
+    padding-right: 1.3em;
+
+    font-size: large;
+    color: #555;
+    line-height: 1.6;
+
+    text-align: justify;
+    overflow-wrap: break-word;
+}
+
+header {
+    font-family: serif;
+    margin-top: 0;
+    margin-bottom: 0.2em;
+    text-align: center;
+}
+
+h1, h2, h3, h4, h5, h6 {
+    margin-top: 0.5em;
+    margin-bottom: 0.2em;
+}
+
+p {
+    margin-top: 0;
+    margin-bottom: 0.8em;
+}
+
+dl {
+    margin-block-start: 0.5em;
+}
+
+tr.odd {
+    background-color: #f7f7f7;
+}
+
+td,th {
+    text-align: left;
+    border: 1px solid #ccc;
+}
+
+</style>
+