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Test Info: Warnings
- This test has a WPT meta file that expects 3 subtest issues.
- This WPT test may be referenced by the following Test IDs:
- /css/css-anchor-position/last-successful-fallback-to-base-style.html - WPT Dashboard Interop Dashboard
<!DOCTYPE html>
<title>CSS Anchor Positioning: switch from using fallback style to base style</title>
<meta name="description" content="Tests a bug in WebKit where if a fallback is initially used, then the base style is used, WebKit will remember the fallback to be the last successful position fallback instead of the base style.">
<link rel="author" title="Kiet Ho" href="mailto:kiet.ho@apple.com">
<link rel="help" href="https://drafts.csswg.org/css-anchor-position/#last-successful-position-fallback">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/test-common.js"></script>
<style>
#container {
position: relative;
width: 600px;
height: 300px;
background: teal;
}
#anchor {
position: relative;
top: 100px;
left: 100px;
width: 100px;
height: 100px;
background: red;
anchor-name: --a;
}
#anchored {
position-anchor: --a;
position-try-fallbacks: flip-inline;
position: absolute;
width: 200px;
height: 100px;
position-area: left center;
background: lime;
}
</style>
<div id="container">
<div id="anchor"></div>
<div id="anchored"></div>
</div>
<script>
promise_test(async () => {
await waitUntilNextAnimationFrame();
await waitUntilNextAnimationFrame();
assert_equals(anchored.offsetLeft, 200);
}, "Starts rendering with flip-inline fallback");
promise_test(async () => {
anchor.style.left = "350px";
await waitUntilNextAnimationFrame();
await waitUntilNextAnimationFrame();
assert_equals(anchored.offsetLeft, 150);
}, "Base position without fallback now successful");
promise_test(async () => {
anchor.style.left = "300px";
await waitUntilNextAnimationFrame();
await waitUntilNextAnimationFrame();
assert_equals(anchored.offsetLeft, 100);
}, "Both base position and flip-inline works, keep base position since it's the last successful option");
</script>