diff --git a/app/assets/javascripts/discourse/app/components/glimmer-site-header.gjs b/app/assets/javascripts/discourse/app/components/glimmer-site-header.gjs
index 3c690da5393..05dbc656800 100644
--- a/app/assets/javascripts/discourse/app/components/glimmer-site-header.gjs
+++ b/app/assets/javascripts/discourse/app/components/glimmer-site-header.gjs
@@ -105,7 +105,16 @@ export default class GlimmerSiteHeader extends Component {
     let headerWrapBottom =
       this._headerWrap.getBoundingClientRect().bottom - overscrollPx;
 
-    // While scrolling on iOS, fixed elements can have a viewport position which fluctuates between -1 and 1.
+    // iOS Safari bug: when overscrolling at the bottom of the page on iOS, fixed/sticky elements report their position incorrectly.
+    // Clamp the headerWrapBottom to the minimum possible value (top + height) to avoid this.
+    const minimumPossibleHeaderWrapBottom =
+      headerCssTop + this._headerWrap.getBoundingClientRect().height;
+    headerWrapBottom = Math.max(
+      headerWrapBottom,
+      minimumPossibleHeaderWrapBottom
+    );
+
+    // Safari bug: while scrolling on iOS, fixed elements can have a viewport position which fluctuates by sub-pixel amounts.
     // To avoid that fluctuation affecting the header offset, we subtract that tiny fluctuation from the header-offset.
     const headerWrapTopDiff =
       this._headerWrap.getBoundingClientRect().top -