From 8ab24b2ebcf99f703f00297cb3a0c3ff857eecf8 Mon Sep 17 00:00:00 2001
From: Julien Palard <julien@palard.fr>
Date: Wed, 8 May 2019 15:32:08 +0200
Subject: [2.7] bpo-24712: Doc: Make sidebar sticky using browser support.
 (GH-13179)

Patch by Mike Taylor.
---
 Doc/tools/static/sidebar.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/Doc/tools/static/sidebar.js b/Doc/tools/static/sidebar.js
index 1bdd829..17f818e 100644
--- a/Doc/tools/static/sidebar.js
+++ b/Doc/tools/static/sidebar.js
@@ -46,6 +46,15 @@ $(function() {
   var dark_color = $('.related').css('background-color');
   var light_color = $('.document').css('background-color');
 
+  // 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;
@@ -157,6 +166,9 @@ $(function() {
 
   /* intelligent scrolling */
   function scroll_sidebar() {
+    if (supportsPositionSticky) {
+      return;
+    }
     var sidebar_height = sidebarwrapper.height();
     var viewport_height = get_viewport_height();
     var offset = sidebar.position()['top'];
-- 
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