diff --git a/Doc/tools/static/sidebar.js b/Doc/tools/static/sidebar.js
--- a/Doc/tools/static/sidebar.js
+++ b/Doc/tools/static/sidebar.js
@@ -40,16 +40,25 @@
   // with the sidebar collapsed
   var bw_margin_collapsed = '.8em';
   var ssb_width_collapsed = '.8em';
 
   // colors used by the current theme
   var dark_color = '#AAAAAA';
   var light_color = '#CCCCCC';
 
+  // set position: sticky on sidebar
+  // (browsers that don't support this will fall-back to
+  // positioning via scroll_sidebar)
+  var supportsPositionSticky = (window.CSS && window.CSS.supports &&
+                                window.CSS.supports('position', 'sticky'));
+  if (supportsPositionSticky) {
+    sidebarwrapper.css('position', 'sticky');
+  }
+
   function get_viewport_height() {
     if (window.innerHeight)
       return window.innerHeight;
     else
       return jwindow.height();
   }
 
   function sidebar_is_collapsed() {
@@ -159,16 +168,19 @@
 
   add_sidebar_button();
   var sidebarbutton = $('#sidebarbutton');
   set_position_from_cookie();
 
 
   /* intelligent scrolling */
   function scroll_sidebar() {
+    if (supportsPositionSticky) {
+      return;
+    }
     var sidebar_height = sidebarwrapper.height();
     var viewport_height = get_viewport_height();
     var offset = sidebar.position()['top'];
     var wintop = jwindow.scrollTop();
     var winbot = wintop + viewport_height;
     var curtop = sidebarwrapper.position()['top'];
     var curbot = curtop + sidebar_height;
     // does sidebar fit in window?