+sub _colors_help ($$) {
+ my ($ctx, $txt) = @_;
+ my $ibx = $ctx->{-inbox};
+ my $env = $ctx->{env};
+ my $base_url = $ibx->base_url($env);
+ $$txt .= "color customization for $base_url\n";
+ $$txt .= <<EOF;
+
+public-inbox provides a stable set of CSS classes for users to
+customize colors for highlighting diffs and code.
+
+Users of browsers such as dillo, Firefox, or some browser
+extensions may start by downloading the following sample CSS file
+to control the colors they see:
+
+ ${base_url}userContent.css
+
+CSS sample
+----------
+```css
+EOF
+ $$txt .= PublicInbox::UserContent::sample($ibx, $env) . "```\n";
+}