Remove Classic Site link from header

Removed link to the Classic WikiPathways site from the header.

Author: mkutmon

_includes/header.html

@@ -42,8 +42,6 @@
               href="/cite.html">Cite</a>
             <a class="nav-item nav-link" style="display:inline;margin-right: 0px;line-height:1;"
               href="/help.html">Help</a>
-              <a class="btn btn-sm btn-front my-1" style="margin-left:0px; font-size: small;display:inline;margin-right: 15px;line-height:1;" 
-              href="https://classic.wikipathways.org" target="_blank">Go to Classic Site</a>
       </div>
     </div>
     </nav>
@@ -54,4 +52,5 @@
   As announced, the Classic WikiPathways site is now <strong>read-only</strong> and the old web service has been turned off. <strong>From 1 May 2026, the Classic site will be fully retired</strong> and we will complete our transition to the new GitHub-based system.<br/>
   <strong>Webservice users:</strong> If you are still using the old web service, please <a href="https://github.com/wikipathways/wikipathways-help/discussions" style="color: #333; text-decoration: underline;">contact us immediately</a> so we can help you transition.<br/>
   <strong>Curators:</strong> PathVisio upload is temporarily unavailable. Please <a href="https://github.com/wikipathways/wikipathways-help/discussions" style="color: #333; text-decoration: underline;">reach out</a> if you need to upload or update a pathway.
+</div>
 </header>