<style>
    dialog::backdrop {
        content: "";
        display: inline-block;
        appearance: slider-vertical;
        width: 16px;
        height: 100px;
    }
</style>
<body>
    <dialog id="dialog"></dialog>
    <p>This test passes if it does not crash.</p>
    <script>
        dialog.showModal();
        if (window.testRunner)
            testRunner.dumpAsText();
    </script>
</body>
