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+++ b/testing/web-platform/tests/css/css-break/flexbox/single-line-row-flex-fragmentation-042-print.html
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+<!DOCTYPE html>
+<html>
+  <meta charset="utf-8">
+  <link rel="author" title="Ting-Yu Lin" href="mailto:tlin@mozilla.com">
+  <link rel="author" title="Mozilla" href="https://www.mozilla.org/">
+  <link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#pagination">
+  <link rel="match" href="single-line-row-flex-fragmentation-042-print-ref.html">
+
+  <style>
+  @page { size: 5in 3in; margin: 0.5in; }
+  body { margin: 0; }
+
+  .flexbox {
+    display: flex;
+    border: 0.25in solid black;
+    font-size: 0.25in;
+  }
+  .item {
+    contain: size;
+    box-sizing: border-box;
+    border: 4px solid purple;
+    width: 25%;
+    height: 0.5in;
+  }
+  </style>
+
+  <!-- This div makes the flexbox not at the top of first page. -->
+  <div style="height: 0.25in; background: gray;"></div>
+
+  <div class="flexbox">
+    <div class="item" style="margin-top: 1in;">1</div>
+    <div class="item">2</div>
+
+    <!-- Due to fragmentation, item 3 is being pushed down and placed at the top
+         of page 2, enlarging the flex container's block-size. Observe item 3
+         and item 4's block-end edges. Before fragmentation, both are at the
+         same level; after fragmentation, item 3's block-end edge becomes lower
+         than item 4's, and making item 4's block-end edge no longer touch the
+         flex container's content-box block-end edge.-->
+    <div class="item" style="margin-top: 1in; height: 1in;">3</div>
+    <div class="item" style="align-self: flex-end;">4</div>
+  </div>
+
+  <div style="height: 0.25in; background: gray;"></div>
+</html>