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diff --git a/testing/web-platform/tests/css/css-scroll-snap/snap-after-relayout/changing-scroll-snap-align.html b/testing/web-platform/tests/css/css-scroll-snap/snap-after-relayout/changing-scroll-snap-align.html
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+++ b/testing/web-platform/tests/css/css-scroll-snap/snap-after-relayout/changing-scroll-snap-align.html
@@ -0,0 +1,121 @@
+<!DOCTYPE html>
+<title>
+  Updating the snap alignment of a snap container's content should make the snap
+  container resnap accordingly.
+</title>
+<link rel="help" href="https://drafts.csswg.org/css-scroll-snap/#re-snap" />
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+div {
+  position: absolute;
+  margin: 0;
+}
+
+#scroller {
+  height: 200px;
+  width: 200px;
+  overflow: hidden;
+  scroll-snap-type: both mandatory;
+}
+
+#initial-target {
+  width: 300px;
+  height: 300px;
+  top: 100px;
+  left: 100px;
+  background-color: green;
+  scroll-snap-align: start;
+}
+
+#other-target {
+  width: 300px;
+  height: 300px;
+  top: 300px;
+  left: 300px;
+  background-color: red;
+  scroll-snap-align: start;
+}
+
+.area {
+  width: 2000px;
+  height: 2000px;
+}
+
+.snap-area {
+  scroll-snap-align: start !important;
+}
+</style>
+
+<div id="scroller">
+  <div class="area"></div>
+  <div id="initial-target"></div>
+  <div id="other-target"></div>
+</div>
+
+<script>
+const initial_target = document.getElementById("initial-target");
+const other_target = document.getElementById("other-target");
+const scroller = document.getElementById("scroller");
+
+function cleanup() {
+  initial_target.style.setProperty("scroll-snap-align", "start");
+  other_target.style.setProperty("scroll-snap-align", "start");
+  initial_target.removeAttribute("class");
+}
+
+test(t => {
+  t.add_cleanup(cleanup);
+  scroller.scrollTo(0,0);
+  assert_equals(scroller.scrollTop, 100);
+  assert_equals(scroller.scrollLeft, 100);
+
+  initial_target.style.setProperty("scroll-snap-align", "end");
+  // target.top + target.height - scroller.height
+  assert_equals(scroller.scrollTop, 200);
+  assert_equals(scroller.scrollLeft, 200);
+}, "Changing the current target's snap alignment should make the scroller"
++ " resnap to it even if another snap position is closer to the current offset");
+
+test(t => {
+  t.add_cleanup(cleanup);
+  scroller.scrollTo(0,0);
+  assert_equals(scroller.scrollTop, 100);
+  assert_equals(scroller.scrollLeft, 100);
+
+  initial_target.style.setProperty("scroll-snap-align", "none");
+  assert_equals(scroller.scrollTop, 300);
+  assert_equals(scroller.scrollLeft, 300);
+}, "Removing the current target's snap alignment should make the scroller"
++ " resnap to a new snap area.");
+
+test(t => {
+  t.add_cleanup(cleanup);
+  initial_target.style.setProperty("scroll-snap-align", "none");
+  other_target.style.setProperty("scroll-snap-align", "none");
+
+  scroller.scrollTo(0,0);
+  assert_equals(scroller.scrollTop, 0);
+  assert_equals(scroller.scrollLeft, 0);
+
+  initial_target.style.setProperty("scroll-snap-align", "start");
+  assert_equals(scroller.scrollTop, 100);
+  assert_equals(scroller.scrollLeft, 100);
+}, "Changing an element snap alignment from none to start should make the"
++ "scroller resnap.");
+
+test(t => {
+  t.add_cleanup(cleanup);
+  initial_target.style.setProperty("scroll-snap-align", "none");
+  other_target.style.setProperty("scroll-snap-align", "none");
+
+  scroller.scrollTo(0,0);
+  assert_equals(scroller.scrollTop, 0);
+  assert_equals(scroller.scrollLeft, 0);
+
+  initial_target.classList.add("snap-area");
+  assert_equals(scroller.scrollTop, 100);
+  assert_equals(scroller.scrollLeft, 100);
+}, "Changing an element snap alignment from none to start by adding a class"
++ " should make the scroller resnap.");
+</script>