From f84d616d6685365a2010e6f5c67cd7ecb68ca515 Mon Sep 17 00:00:00 2001
From: Adam Wood <1017872+adamwoodnz@users.noreply.github.com>
Date: Wed, 11 Dec 2024 10:10:18 +1300
Subject: [PATCH] Sidebar container: Only observe main sidebar height when
 floating

This avoids setting a min-height on main on smaller devices, leading to longer than necessary page lengths.

See https://github.com/WordPress/wporg-mu-plugins/issues/611
---
 mu-plugins/blocks/sidebar-container/src/view.js | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/mu-plugins/blocks/sidebar-container/src/view.js b/mu-plugins/blocks/sidebar-container/src/view.js
index 7b797b8e..6f5455f0 100644
--- a/mu-plugins/blocks/sidebar-container/src/view.js
+++ b/mu-plugins/blocks/sidebar-container/src/view.js
@@ -106,13 +106,16 @@ function init() {
 			// When the sidebar container adjacent to the main element (usually the chapter list)
 			// is taller than the main element, a glitch occurs when scrolling past the point where
 			// the sidebar becomes fixed, because the main element height depends on the sidebar container
-			// height. To avoid this, we observe the height of this container when it is not fixed, and
-			// set the min-height of the main element to match the container height.
+			// height. To avoid this, we observe the height of this container when it is floating and
+			// not fixed, and set the min-height of the main element to match the container height.
 			const isSibling = container.previousElementSibling === main || container.nextElementSibling === main;
 			if ( 'ResizeObserver' in window && isSibling ) {
 				const resizeObserver = new ResizeObserver( ( entries ) => {
 					for ( const entry of entries ) {
-						if ( ! container.classList.contains( 'is-fixed-sidebar' ) ) {
+						if (
+							container.classList.contains( 'is-floating-sidebar' ) &&
+							! container.classList.contains( 'is-fixed-sidebar' )
+						) {
 							const containerHeight = entry.contentRect.height;
 
 							if ( containerHeight ) {