From 1fb409e521a54f70e10bfa720358356cca6e6834 Mon Sep 17 00:00:00 2001
From: Robin Ward <robin.ward@gmail.com>
Date: Wed, 8 Nov 2017 16:34:35 -0500
Subject: [PATCH] FIX: Use `offset` to calculate eyeline, which is safer than
 `position`

---
 .../discourse/components/scrolling-post-stream.js.es6      | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/app/assets/javascripts/discourse/components/scrolling-post-stream.js.es6 b/app/assets/javascripts/discourse/components/scrolling-post-stream.js.es6
index 87e59f60bae..d3595914c66 100644
--- a/app/assets/javascripts/discourse/components/scrolling-post-stream.js.es6
+++ b/app/assets/javascripts/discourse/components/scrolling-post-stream.js.es6
@@ -4,13 +4,13 @@ import { cloak, uncloak } from 'discourse/widgets/post-stream';
 import { isWorkaroundActive } from 'discourse/lib/safari-hacks';
 import offsetCalculator from 'discourse/lib/offset-calculator';
 
-function findTopView($posts, viewportTop, min, max) {
+function findTopView($posts, viewportTop, postsWrapperTop, min, max) {
   if (max < min) { return min; }
 
   while (max > min) {
     const mid = Math.floor((min + max) / 2);
     const $post = $($posts[mid]);
-    const viewBottom = $post.position().top + $post.height();
+    const viewBottom = ($post.offset().top - postsWrapperTop) + $post.height();
 
     if (viewBottom > viewportTop) {
       max = mid-1;
@@ -71,9 +71,10 @@ export default MountWidget.extend({
 
     const windowTop = $w.scrollTop();
 
+    const postsWrapperTop = $('.posts-wrapper').offset().top;
     const $posts = this.$('.onscreen-post, .cloaked-post');
     const viewportTop = windowTop - slack;
-    const topView = findTopView($posts, viewportTop, 0, $posts.length-1);
+    const topView = findTopView($posts, viewportTop, postsWrapperTop, 0, $posts.length-1);
 
     let windowBottom = windowTop + windowHeight;
     let viewportBottom = windowBottom + slack;