Use GNU manual CSS for HTML texinfo documentation

with custom added support for dark mode.

Author: afh

custom_theme/sass/darkmode.scss

@@ -4,12 +4,14 @@
   --light-highlight-code-background-color:#eee;
   --light-link-color:#00e;
   --light-visited-color:#551a8b;
+  --light-example-brightness:95%;
 
   --dark-color:#fefefe;
   --dark-background-color:#212121;
   --dark-highlight-code-background-color:#333;
   --dark-link-color:#2997ff;
   --dark-visited-color:#aa6fdf;
+  --dark-example-brightness:125%;
 }
 
 @media (prefers-color-scheme: light) {
@@ -19,6 +21,7 @@
     --highlight-code-background-color:var(--light-highlight-code-background-color);
     --link-color:var(--light-link-color);
     --visited-color:var(--light-visited-color);
+    --example-brightness:var(--light-example-brightness);
   }
 }
 @media (prefers-color-scheme: dark) {
@@ -28,6 +31,7 @@
     --highlight-code-background-color:var(--dark-highlight-code-background-color);
     --link-color:var(--dark-link-color);
     --visited-color:var(--dark-visited-color);
+    --example-brightness:var(--dark-example-brightness);
   }
 }
 

custom_theme/sass/doc.scss

@@ -1,15 +1,25 @@
 @import url("darkmode.css");
 
-body {
+body, html {
   color:var(--color);
   background:var(--background-color);
 }
 
-:link {
-  color:var(--link-color);
+h1, h2, h3, h4 {
+  color:var(--color);
+}
+
+div.example {
+  color:var(--color);
+  background:var(--background-color);
+  filter:brightness(var(--example-brightness));
+}
+
+:link, a[href]:hover {
+  color:var(--link-color) !important;
 }
 
-:visited {
-  color:var(--visited-color);
+a[href]:visited {
+  color:var(--visited-color) !important;
 }
 

flake.nix

@@ -90,7 +90,7 @@
            # Create print version of ledger manpage
            pdfroff -man -dpaper=letter -P-pletter $src/doc/ledger.1 > ledger.1.pdf
            # Patch web version of ledger manual to support dark mode
-           sed -e 's@</style>@&<link rel="stylesheet" type="text/css" href="/css/doc.css">@' ledger3.html -i
+           sed -e 's@</style>@&\n<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/g  nulib/manual.css"><link rel="stylesheet" type="text/css" href="/stylesheets/doc.css">@' ledger3.html -i
            '';
 
          postInstall = ''
@@ -117,7 +117,7 @@
            texi2pdf --batch ledger-mode.texi
            makeinfo --force --html --no-split ledger-mode.texi
            # Patch web version of ledger mode manual to support dark mode
-           sed -e 's@</style>@&<link rel="stylesheet" type="text/css" href="/css/doc.css">@' ledger-mode.html -i
+           sed -e 's@</style>@&\n<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/g  nulib/manual.css"><link rel="stylesheet" type="text/css" href="/stylesheets/doc.css">@' ledger-mode.html -i
            runHook postBuild
          '';