+my $default_theme = 'cyborg';
+
+sub theme_prefix {
+ my ($theme, $decl, $default) = @_;
+ return $decl if $theme eq $default_theme || !$decl;
+ return '' if $decl eq $default;
+
+ $default =~ s/[^{]*{\n//;
+ $default =~ s/\n}[^}]*//;
+ $decl =~ s/^$_$//m for split "\n", $default;
+ $decl =~ s/\n+/\n/g;
+
+ my $prefix = "html.$theme";
+ my ($first_line) = $decl =~ /([^{]*){/;
+ $first_line =~ s/(,\s+)/$1 $prefix /g;
+ $first_line = "$prefix $first_line";
+ $decl =~ s/([^{]*){/$first_line\{/;
+ $decl
+}
+