<!DOCTYPE html>
<!--
 | Wrapping is only performed at an allowed break point, called a soft wrap
 | opportunity. In most writing systems, in the absence of hyphenation a soft
 | wrap opportunity occurs only at word boundaries.
 |   https://www.w3.org/TR/css3-text/#soft-wrap-opportunity
 |   https://www.w3.org/TR/css-text-3/#line-break-details
 |
 | All soft wrap segments that can fully fit within the available width will be
 | included on the line.
 -->
<html>
<head>
  <style>
    body {
      margin: 0px;
      font-family: Roboto;
      font-size: 20px;
    }
    div {
      word-wrap: break-word;
    }
    .containing-block {
      background-color: #03a9f4;
      width: 110px;
    }
  </style>
</head>
<body>
  <div class="containing-block">
    <div>abcd<span>ef gh</span>i jkl</div>
    <div>ab cd<span>efgh</span> ijkl</div>
    <div>abcd<span>ef gh </span>ijkl</div>
    <div>abcd <span>ef gh</span>ijkl</div>
    <div>ab cd<span> efgh</span>ijkl</div>
    <div>ab cd <span>efgh</span>ijkl</div>
    <div>ab c d<span>efgh</span>ijkl</div>
    <div> abcd<span>efgh</span>ijkl</div>
  </div>
</body>
</html>