css/css-multicol/multicol-span-all-button-002.html

<!DOCTYPE html>
<html>
  <meta charset="utf-8">
  <title>CSS Multi-column Layout Test: Test a overflow:hidden and position:absolute multi-column container on button works with a column-span:all child and position:absolute boxes</title>
  <link rel="author" title="Ting-Yu Lin" href="mailto:tlin@mozilla.com">
  <link rel="author" title="Mozilla" href="http://www.mozilla.org/">
  <link rel="help" href="https://drafts.csswg.org/css-multicol-1/#column-span">
  <link rel="match" href="multicol-span-all-button-002-ref.html">
  <meta name="assert" content="This test checks the page is rendered correctly for a overflow:hidden and position:absolute button multi-column container with a column-span:all child and position:absolute boxes.">

  <style>
  button {
    column-count: 3;
    column-rule: 6px solid;
    width: 400px;
    padding: 1em;
    overflow: hidden;
    position: absolute;
  }
  h3 {
    column-span: all;
    outline: 1px solid blue;
  }
  a {
    position: absolute;
    width: 1em;
    height: 1em;
    background-color: blue;
  }
  </style>

  <button>
    <div>block1</div><div>block2</div><a></a>
    <h3>spanner<a></a></h3>
    <div>block3</div><div>block4</div><a></a>
  </button>
</html>