<!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. However, when the
 | word-wrap property has a value of break-word, unbreakable "words" may be
 | broken at an arbitrary point to prevent overflow, while still preserving
 | grapheme clusters.
 |   https://www.w3.org/TR/css3-text/#soft-wrap-opportunity
 |   https://www.w3.org/TR/css-text-3/#line-break-details
 |   https://www.w3.org/TR/css-text-3/#word-wrap
 |
 | On overflow, the first available break point will be selected. With word-wrap
 | normal, this will be the first soft-wrap location. With word-wrap break-word,
 | this will be at the first grapheme cluster boundary.
 -->
<html>
<head>
  <style>
    body {
      margin: 0px;
      font-family: Roboto;
      font-size: 20px;
    }
    div {
      overflow-wrap: normal;
    }
    .containing-block {
      background-color: #03a9f4;
      width: 100px;
    }
  </style>
</head>
<body>
  <div class="containing-block">
    <div><span>abcdefghijklm n <span>o p</span> qr<span>st</span></span></div>
    <div><span>abcdefghijklmn <span>o p</span> qr<span>st</span></span></div>
    <div><span>abcdefghijklmn<span>o p </span> qr<span>s t</span></span></div>
    <div><span>abcdefghijklmn<span>op </span> qr<span>s t</span></span></div>
    <div><span>abcdefghijklmn<span>op</span> q r <span> st</span></span></div>
    <div><span>abcdefghijklmn<span>op</span>q r <span> s t</span></span></div>
    <div><span>abcdefghijklmn<span>op</span>qr <span>st</span></span></div>
    <div><span>abcdefghijklmn<span>op</span>qr<span>st</span></span></div>
  </div>
</body>
</html>