<div style="-webkit-writing-mode: horizontal-bt;">
    <div style="
        margin-top: 300px;
        outline: dashed lightblue;
        height: 100px;
        width: 100px;
        border-bottom: 25px solid;
        -webkit-column-axis: vertical;
        -webkit-column-gap: 50px;
    ">
        <div style="height: 100px; background-color: silver;"></div>
        <div id="target" style="height: 100px; background-color: silver;"></div>
        <div style="height: 100px; background-color: silver;"></div>
    </div>
</div>
<p id="result">FAIL: Test did not run.</p>
<script>
    if (window.testRunner)
        testRunner.dumpAsText();

    var hitContainer = document.caretRangeFromPoint(208, 208).startContainer;
    var target = document.getElementById("target");
    document.getElementById("result").innerText = hitContainer === target ? "PASS" : "FAIL";
</script>