From 9142178b113443749b87c1d259859b42a3d7a9c4 Mon Sep 17 00:00:00 2001
From: Martin Trapp <94928215+martrapp@users.noreply.github.com>
Date: Tue, 22 Aug 2023 19:33:49 +0200
Subject: [PATCH] Mt scroll behavior (#8184)

* The scrolling behavior of ViewTransition is now more similar to the expected browser behavior

* format

* removed browser detection
---
 .changeset/pretty-dancers-admire.md           |  5 +++++
 .../astro/components/ViewTransitions.astro    | 19 +++++++++++++------
 2 files changed, 18 insertions(+), 6 deletions(-)
 create mode 100644 .changeset/pretty-dancers-admire.md

diff --git a/.changeset/pretty-dancers-admire.md b/.changeset/pretty-dancers-admire.md
new file mode 100644
index 000000000000..13553488b6b3
--- /dev/null
+++ b/.changeset/pretty-dancers-admire.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix: The scrolling behavior of ViewTransitions is now more similar to the expected browser behavior
diff --git a/packages/astro/components/ViewTransitions.astro b/packages/astro/components/ViewTransitions.astro
index 12dfe0f4f70a..612b89659b8d 100644
--- a/packages/astro/components/ViewTransitions.astro
+++ b/packages/astro/components/ViewTransitions.astro
@@ -164,14 +164,21 @@ const { fallback = 'animate' } = Astro.props as Props;
 				}
 			}
 
+			// Simulate scroll behavior of Safari and
+			// Chromium based browsers (Chrome, Edge, Opera, ...)
+			scrollTo({ left: 0, top: 0, behavior: 'instant' });
+
 			if (state?.scrollY === 0 && location.hash) {
 				const id = decodeURIComponent(location.hash.slice(1));
-				state.scrollY = document.getElementById(id)?.offsetTop || 0;
-			}
-			if (state?.scrollY != null) {
-				scrollTo(0, state.scrollY);
-				// Overwrite erroneous updates by the scroll handler during transition
-				persistState(state);
+				const elem = document.getElementById(id);
+				// prefer scrollIntoView() over scrollTo() because it takes scroll-padding into account
+				if (elem) {
+					state.scrollY = elem.offsetTop;
+					persistState(state); // first guess, later updated by scroll handler
+					elem.scrollIntoView(); // for Firefox, this should better be {behavior: 'instant'}
+				}
+			} else if (state && state.scrollY !== 0) {
+				scrollTo(0, state.scrollY); // usings default scrollBehavior
 			}
 
 			triggerEvent('astro:beforeload');