chromium/third_party/blink/web_tests/external/wpt/css/css-multicol/multicol-dynamic-add-001.html

<!DOCTYPE html>
<html class="reftest-wait">
  <meta charset="utf-8">
  <title>CSS Multi-column Layout Test: Append a block to an empty inline element</title>
  <link rel="author" title="Ting-Yu Lin" href="mailto:[email protected]">
  <link rel="author" title="Mozilla" href="http://www.mozilla.org/">
  <link rel="help" href="https://drafts.csswg.org/css-multicol-1/#cf">
  <link rel="help" href="https://www.w3.org/TR/CSS22/visuren.html#anonymous-block-level">
  <link rel="match" href="multicol-dynamic-add-001-ref.html">
  <meta name="assert" content="This test checks that the block appended into an inline element should perform correct block-in-inline splitting, and balance the block's height into three columns.">

  <script>
  function runTest() {
    document.body.offsetHeight;

    /* Append a block to the inline element. */
    var block = document.createElement("div");
    var text = document.createTextNode("block");
    block.appendChild(text);

    var span = document.getElementById("span");
    span.appendChild(block);

    document.documentElement.removeAttribute("class");
  }
  </script>

  <style>
  #column {
    column-count: 3;
    column-rule: 6px solid;
    width: 400px;
    outline: 1px solid black;
  }
  div {
    height: 300px;
    background-color: yellow;
  }
  </style>

  <body onload="runTest();">
    <article id="column">
      <span id="span"><!-- block will be added here. --></span>
    </article>
  </body>
</html>