<!DOCTYPE html>
<html>
  <head>
    <title>Multicol edge clipping</title>
    <style>
      .mc {
        columns: 3;
        column-gap: 15px;
        column-fill: auto;
        -webkit-columns: 3;
        -webkit-column-gap: 15px;
        -webkit-column-fill: auto;
        width: 600px;
        height: 100px;
        margin: 100px;
        overflow:hidden;
      }
    </style>
  </head>
  <body>
    <p>There should be a 100x100 blue square below.</p>
    <div class="mc">
      <div style="width:150px; height:200px; margin-left:-50px; margin-top:-100px; background:blue;"></div>
    </div>
  </body>
</html>