1 files changed, 62 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-position/sticky/position-sticky-table-th-left-ref.html b/testing/web-platform/tests/css/css-position/sticky/position-sticky-table-th-left-ref.html
new file mode 100644
index 0000000000..7d0e5f9e58
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+++ b/testing/web-platform/tests/css/css-position/sticky/position-sticky-table-th-left-ref.html
@@ -0,0 +1,62 @@
+<!DOCTYPE html>
+<title>Reference for position:sticky left constraint should behave correctly for &lt;th&gt; elements</title>
+
+<style>
+.group {
+  position: relative;
+  width: 250px;
+  height: 150px;
+}
+
+.scroller {
+  position: relative;
+  width: 200px;
+  height: 100px;
+  overflow-x: auto;
+  overflow-y: hidden;
+}
+
+.contents {
+  height: 10px;
+  width: 500px;
+}
+
+.indicator {
+  position: absolute;
+  background-color: green;
+  top: 0;
+  height: 50px;
+  width: 50px;
+}
+</style>
+
+<script>
+window.addEventListener('load', function() {
+  document.getElementById('scroller1').scrollLeft = 50;
+  document.getElementById('scroller2').scrollLeft = 125;
+  document.getElementById('scroller3').scrollLeft = 250;
+});
+</script>
+
+<div>You should see three green boxes below. No red or blue should be visible.</div>
+
+<div class="group">
+  <div id="scroller1" class="scroller">
+    <div class="indicator" style="left: 100px;"></div>
+    <div class="contents"></div>
+  </div>
+</div>
+
+<div class="group">
+  <div id="scroller2" class="scroller">
+    <div class="indicator" style="left: 150px;"></div>
+    <div class="contents"></div>
+  </div>
+</div>
+
+<div class="group">
+  <div id="scroller3" class="scroller">
+    <div class="indicator" style="left: 250px;"></div>
+    <div class="contents"></div>
+  </div>
+</div>