css/css-text/line-breaking/line-breaking-022.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Text Test: Simple line breaking test</title>
<link rel="author" title="Florian Rivoal" href="https://florian.rivoal.net">
<link rel="help" href="https://drafts.csswg.org/css-text-3/#line-break-details">
<link rel="match" href="reference/line-reabking-022.html">
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" >
<meta name="flags" content="ahem" >
<meta name=assert content="Any Unicode character with the the BK and NL line breaking class must be treated as forced line breaks">
<style>
div {
  font: 25px/1 Ahem;
  color: transparent; /* No interested in the rendering of the characters with BK an ML line breaking classes themselves, merely in their effects on line breaking. */
}
span { color: green; }
.red {
  z-index: -1;
  position: absolute;
  width: 1em;
  height: 6em;
  background: red;
}
</style>

<p>This test passes if there is no red.

<div class=red></div>

<div>
<span>1</span>&#x000C;<span>2</span>&#x000B;<span>3</span>&#x2028;<span>4</span>&#x2029;<span>5</span>&#x0085;<span>6</span>
</div>