diff --git a/framework/core/less/forum/DiscussionPage.less b/framework/core/less/forum/DiscussionPage.less
index d2155602b..3f7b1123f 100644
--- a/framework/core/less/forum/DiscussionPage.less
+++ b/framework/core/less/forum/DiscussionPage.less
@@ -71,11 +71,11 @@
   .DiscussionPage-list {
     left: -@pane-width;
     width: 100%;
-    position: fixed;
+    position: absolute;
     z-index: @zindex-pane;
     overflow: auto;
     top: @header-height;
-    bottom: 0;
+    height: ~"calc(100vh - @{header-height})";
     width: @pane-width;
     background: @body-bg;
     padding-bottom: 40px;
@@ -83,6 +83,11 @@
     .box-shadow(2px 2px 6px -2px @shadow-color);
     .transition(left 0.2s);
 
+    .affix & {
+      position: fixed;
+      bottom: 0;
+      height: auto;
+    }
     .paneShowing & {
       left: 0;
     }