Insert in your Stylesheet tweaks to get black---instead of gray--text when pages are printed.

@media print {
    body {
        color: black;
        background-color: white;
        font-size: 10pt;
    }

    h1, h2, h3, h4, h5, h6 {
        color: black;
    }

    a, a:link, a:active, a:visited {
        color: black;
        border-bottom: thin dotted;
        text-decoration: none;
    }

 h1#pageName, .newWikiWord a, a.existingWikiWord, .newWikiWord a:hover, #TextileHelp h3 { 
      color: black; 
    }
}

Failed to apply changes :
[Fri Nov 18 05:06:50 2005] [notice] suEXEC mechanism enabled (wrapper: /usr/local/sbin/suexec)
[Fri Nov 18 05:06:52 2005] [notice] FastCGI: wrapper mechanism enabled (wrapper: /usr/local/sbin/suexec)
[Fri Nov 18 05:06:52 2005] [notice] FastCGI: process manager initialized (pid 77504)
[Fri Nov 18 05:06:52 2005] [notice] Digest: generating secret for digest authentication ...
[Fri Nov 18 05:06:52 2005] [notice] Digest: done

/usr/local/bin/ruby /home/rsimplicio/web/instiki/instiki.rb --daemon --port 8966 --storage /home/rsimplicio/web/instiki/storage/