diff --git a/main/404.html b/main/404.html
index 9313e91d..f31d3b47 100644
--- a/main/404.html
+++ b/main/404.html
@@ -39,6 +39,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul>
 <form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off">
diff --git a/main/CODE_OF_CONDUCT.html b/main/CODE_OF_CONDUCT.html
index 0ed43a89..4e30b0e1 100644
--- a/main/CODE_OF_CONDUCT.html
+++ b/main/CODE_OF_CONDUCT.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/CONTRIBUTING.html b/main/CONTRIBUTING.html
index 3bfac469..e729f92c 100644
--- a/main/CONTRIBUTING.html
+++ b/main/CONTRIBUTING.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/LICENSE.html b/main/LICENSE.html
index 181fc6cf..953bb800 100644
--- a/main/LICENSE.html
+++ b/main/LICENSE.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/authors.html b/main/authors.html
index 5e39314e..459cb174 100644
--- a/main/authors.html
+++ b/main/authors.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/index.html b/main/index.html
index b7a0ecfc..6df056d3 100644
--- a/main/index.html
+++ b/main/index.html
@@ -45,6 +45,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul>
 <form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off">
diff --git a/main/news/index.html b/main/news/index.html
index 0ff16eba..dedb323e 100644
--- a/main/news/index.html
+++ b/main/news/index.html
@@ -24,6 +24,12 @@
 <li class="active nav-item">
   <a class="nav-link" href="../news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="../search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/pull_request_template.html b/main/pull_request_template.html
index 56fd2e0b..27bb541d 100644
--- a/main/pull_request_template.html
+++ b/main/pull_request_template.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/reference/index.html b/main/reference/index.html
index 5e1d2716..630846bc 100644
--- a/main/reference/index.html
+++ b/main/reference/index.html
@@ -24,6 +24,12 @@
 <li class="nav-item">
   <a class="nav-link" href="../news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="../search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>
 
diff --git a/main/reference/sdtm.oak.html b/main/reference/sdtm.oak.html
index 43c65a2f..ba0dd9a7 100644
--- a/main/reference/sdtm.oak.html
+++ b/main/reference/sdtm.oak.html
@@ -32,6 +32,12 @@
 <li class="nav-item">
   <a class="nav-link" href="../news/index.html">Changelog</a>
 </li>
+<!-- start dropdown for versions --> <li class="nav-item dropdown">
+        <a href="#" class="nav-link dropdown-toggle"
+          data-bs-toggle="dropdown" role="button"
+          aria-expanded="false" aria-haspopup="true"
+          id="dropdown-versions">Versions</a> <div class="dropdown-menu" aria-labelledby="dropdown-versions"> <a class="dropdown-item" data-toggle="tooltip" title="" href="https://pharmaverse.github.io/oak/main">main</a> </div></li>
+<!-- end dropdown for versions -->
       </ul><form class="form-inline my-2 my-lg-0" role="search">
         <input type="search" class="form-control me-sm-2" aria-label="Toggle navigation" name="search-input" data-search-index="../search.json" id="search-input" placeholder="Search for" autocomplete="off"></form>