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Test Info:
- This WPT test may be referenced by the following Test IDs:
- /css/css-contain/container-queries/backdrop-invalidation.html - WPT Dashboard Interop Dashboard
<!doctype html>
<title>Test that ::backdrop responds to container size changes</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/cq-testcommon.js"></script>
<style>
:root {
color: black;
}
#container {
container-type: size;
width: 200px;
height: 40px;
}
::backdrop {
background-color: black;
}
@container (min-width: 300px) {
::backdrop {
background-color: green;
}
}
</style>
<main id=container>
<dialog>test</dialog>
</main>
<script>
setup(() => assert_implements_container_queries());
let dialog = document.querySelector('dialog');
test(function() {
try {
dialog.showModal();
assert_equals(getComputedStyle(dialog, '::backdrop').backgroundColor, 'rgb(0, 0, 0)');
container.style.width = '300px';
assert_equals(getComputedStyle(dialog, '::backdrop').backgroundColor, 'rgb(0, 128, 0)');
container.style = '';
assert_equals(getComputedStyle(dialog, '::backdrop').backgroundColor, 'rgb(0, 0, 0)');
} finally {
dialog.close();
}
}, 'Pseudo-element ::backdrop responds to container size changes');
</script>