styles-source-lines-inline-helper.html

<html>
<head>
<style>
.foo {
    color: blue;
}
</style>
</head>

<body>

<div id="foo" class="foo" style="display:none">Foo</div>
<iframe src="../../styles/resources/styles-source-lines-inline-iframe.html">

</body>
</html>

chromium/third_party/blink/web_tests/http/tests/devtools/elements/styles-4/resources/styles-source-lines-inline-helper.html