[css-ruby] Changed the obsoletion notice to a <details>.

Author: tabatkins

css-ruby/Overview.html

@@ -100,7 +100,10 @@ <h2 class="no-num no-toc" id="w3c-working">W3C Working Draft 03 December 2010 (E
 </div>
 <hr />
 
-<p style="background: #fdd; color: red; font-weight: bold; text-align: center; padding: .5em; border: thick solid red; border-radius: 1em; position: fixed; bottom: 1em; left: 1em; right: 1em;">This specification is not being actively maintained, and should not be used as a guide for implementations.  It may be revived in the future, but for now should be considered obsolete.  <br>If you have questions or comments on this specification, please send an email to the CSS Working Group's mailing list at <a href="mailto:www-style@w3.org">www-style@w3.org</a>.  (Before sending mail for the first time, you have to subscribe at <a href="http://lists.w3.org/Archives/Public/www-style/">http://lists.w3.org/Archives/Public/www-style/</a>.)</p>
+<details open class='obsolete'>
+  <summary>Not Actively Maintained</summary>
+  <p>This specification is not being actively maintained, and should not be used as a guide for implementations.  It may be revived in the future, but for now should be considered obsolete.  <br>If you have questions or comments on this specification, please send an email to the CSS Working Group's mailing list at <a href="mailto:www-style@w3.org">www-style@w3.org</a>.  (Before sending mail for the first time, you have to subscribe at <a href="http://lists.w3.org/Archives/Public/www-style/">http://lists.w3.org/Archives/Public/www-style/</a>.)
+</details>
 
 <h2><a id="Abstract">Abstract</a></h2>