css/css-content/element-replacement-dynamic.html

<!DOCTYPE html>
<html class="reftest-wait">
<meta charset="utf-8">
<title>The content CSS attribute can replace an element's contents dynamically</title>
<link rel="author" title="Oriol Brufau" href="mailto:obrufau@igalia.com" />
<link rel="match" href="element-replacement-ref.html" />
<link rel="help" href="https://drafts.csswg.org/css-content-3/#content-property" />
<meta name="assert" content="This test checks that the CSS content propertly can replace a normal element's contents when changed dynamically" />

<script src="/common/reftest-wait.js"></script>
<script src="/common/rendering-utils.js"></script>

<style>
#target {
  content: none;
}
#target.replaced {
  content: url('resources/rect.svg');
}
</style>

<div id="target">This text should not be visible</div>

<script>
waitForAtLeastOneFrame().then(() => {
  document.getElementById("target").className = "replaced";
  takeScreenshot();
});
</script>