<!DOCTYPE html>
<!--
 | The value "pre" of property "white-space" does not allow wrapping. Content
 | that does not fit the block container overflows it. The spec states that
 | spaces should be treated as non-breaking spaces within white-space pre. As
 | a result, when doing line-breaking analysis, any leading space in a
 | white-space pre box is treated as a non-breaking space, and any space
 | preceding a pre box will always be breakable.
 |   https://www.w3.org/TR/css3-text/#white-space-property
 |   https://www.w3.org/TR/CSS2/text.html#white-space-model
 |   http://unicode.org/reports/tr14/#Algorithm
 -->
<html>
<head>
  <style>
    body {
      margin: 0px;
      font-family: Roboto;
      font-size: 18px;
    }
    div {
      background-color: #03a9f4;
      width: 100px;
    }
    .pre-box {
      white-space: pre;
    }
    video {
      background-color: #f50057;
      width: 80px;
      height: 20px;
    }
    .inline-block {
      background-color: #aeea00;
      display: inline-block;
      width: 80px;
      height: 20px;
    }
  </style>
</head>
<body>
  <div>abc <span class="pre-box">  ABCDEF</span></div>
  <div><span>abc <span class="pre-box">  ABCDEF</span></span></div>
  <div>abc <span class="pre-box">ABCDEF</span></div>
  <div><span>abc <span class="pre-box">ABCDEF</span></span></div>
  <div>abc <span class="pre-box"><video></video></span></div>
  <div><span>abc <span class="pre-box"><video></video></span></span></div>
  <div>abc <span class="pre-box"><span class="inline-block"></span></span></div>
  <div><span>abc <span class="pre-box"><span class="inline-block"></span></span></span></div>
</body>
</html>