unfortunately Collapse and therefore also jquery are required :/

bootstrap/css/bootstrap-theme.css

@@ -5,8 +5,8 @@
  */
 
 /*!
- * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=f8d5fd8296f89ec97a16)
- * Config saved to config.json and https://gist.github.com/f8d5fd8296f89ec97a16
+ * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=3c7c656f52fd3ed09ab6)
+ * Config saved to config.json and https://gist.github.com/3c7c656f52fd3ed09ab6
  */
 /*!
  * Bootstrap v3.3.6 (http://getbootstrap.com)

bootstrap/css/bootstrap-theme.min.css

@@ -5,8 +5,8 @@
  */
 
 /*!
- * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=f8d5fd8296f89ec97a16)
- * Config saved to config.json and https://gist.github.com/f8d5fd8296f89ec97a16
+ * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=3c7c656f52fd3ed09ab6)
+ * Config saved to config.json and https://gist.github.com/3c7c656f52fd3ed09ab6
  *//*!
  * Bootstrap v3.3.6 (http://getbootstrap.com)
  * Copyright 2011-2015 Twitter, Inc.

bootstrap/css/bootstrap.css

@@ -5,8 +5,8 @@
  */
 
 /*!
- * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=f8d5fd8296f89ec97a16)
- * Config saved to config.json and https://gist.github.com/f8d5fd8296f89ec97a16
+ * Generated using the Bootstrap Customizer (http://getbootstrap.com/customize/?id=3c7c656f52fd3ed09ab6)
+ * Config saved to config.json and https://gist.github.com/3c7c656f52fd3ed09ab6
  */
 /*!
  * Bootstrap v3.3.6 (http://getbootstrap.com)
@@ -1835,6 +1835,41 @@ select[multiple].input-lg {
     font-size: 12px;
   }
 }
+.fade {
+  opacity: 0;
+  -webkit-transition: opacity 0.15s linear;
+  -o-transition: opacity 0.15s linear;
+  transition: opacity 0.15s linear;
+}
+.fade.in {
+  opacity: 1;
+}
+.collapse {
+  display: none;
+}
+.collapse.in {
+  display: block;
+}
+tr.collapse.in {
+  display: table-row;
+}
+tbody.collapse.in {
+  display: table-row-group;
+}
+.collapsing {
+  position: relative;
+  height: 0;
+  overflow: hidden;
+  -webkit-transition-property: height, visibility;
+  -o-transition-property: height, visibility;
+     transition-property: height, visibility;
+  -webkit-transition-duration: 0.35s;
+  -o-transition-duration: 0.35s;
+     transition-duration: 0.35s;
+  -webkit-transition-timing-function: ease;
+  -o-transition-timing-function: ease;
+     transition-timing-function: ease;
+}
 .nav {
   margin-bottom: 0;
   padding-left: 0;