css/css-sizing/aspect-ratio-automatic-minimum.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>aspect-ratio with height:0 and explicit min-width:0 should produce 0 content width</title>
<link rel="help" href="https://drafts.csswg.org/css-sizing-4/#aspect-ratio-minimum">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.test {
    aspect-ratio: 1;
    width: max-content;
    height: 0;
    border-top: 25px solid cyan;
}
.test::before {
    content: "X";
}
</style>
<div class="test" id="explicit-zero" style="min-width: 0"></div>
<div class="test" id="auto-minimum" style="min-width: auto"></div>
<script>
test(function() {
    assert_equals(document.getElementById('explicit-zero').clientWidth, 0,
        'content-box width should be 0 (aspect-ratio transfers height:0)');
}, 'min-width:0 disables automatic minimum');

test(function() {
    assert_greater_than(document.getElementById('auto-minimum').clientWidth, 0,
        'content-box width should be > 0 (automatic minimum applies)');
}, 'min-width:auto enables automatic minimum');
</script>