Pass condition: orange square is vertically centered in the black box.
Chrome 112 and Safari 16.4 fail. Firefox 111 passes.

Summary

Harness status: OK

Found 1 tests

Details

ResultTest NameMessage
Fail.flexitem + .flexitem 1assert_equals: <div class="flexitem" style="background: orange; height: 100px;" data-offset-y="50"></div> offsetTop expected 50 but got 0
    at assert_tolerance (https://xn--n8j6ds53lwwkrqhv28a.wpt.live/resources/check-layout-th.js:24:9)
    at checkExpectedValues (https://xn--n8j6ds53lwwkrqhv28a.wpt.live/resources/check-layout-th.js:87:9)
    at checkSubtreeExpectedValues (https://xn--n8j6ds53lwwkrqhv28a.wpt.live/resources/check-layout-th.js:7:25)
    at Test.<anonymous> (https://xn--n8j6ds53lwwkrqhv28a.wpt.live/resources/check-layout-th.js:229:34)
    at Test.step (https://xn--n8j6ds53lwwkrqhv28a.wpt.live/resources/testharness.js:2684:25)
Asserts run
Pass
assert_true(true, "data-offset-y is a valid data attribute")
    at checkDataKeys ( /resources/check-layout-th.js:61:13)
Fail
assert_equals(0, 50, "\n<div class=\"flexitem\" style=\"background: orange; height: 100px;\" data-offset-y=\"50\"></div>\noffsetTop")
    at assert_tolerance ( /resources/check-layout-th.js:24:9)