chromium/third_party/blink/web_tests/external/wpt/css/css-flexbox/percentage-heights-004.html

<!DOCTYPE html>
<html>
<title>CSS Flexbox: Percentages in stretched container</title>
<link rel="author" title="Google" href="https://www.google.com/" />
<link rel="help" href="https://drafts.csswg.org/css-flexbox-1/#definite-sizes" />
<link rel="match" href="percentage-heights-004-ref.html">

<style>
#outer {
  height: 10em;
  display: inline-flex;
  background: tan;
}

#middle {
  overflow-x: scroll;
}

#inner {
  width: 200px;
  height: 100%;
  background: green;
}

#outer2 {
  height: 10em;
  display: inline-flex;
  flex-direction: column;
  background: tan;
}

#middle2 {
  overflow-x: scroll;
  flex: 1.0;
}

#inner2 {
  width: 200px;
  height: 100%;
  background: green;
}
</style>

<p>You should not see tan (except perhaps as the background of a horizontal
   scrollbar), and you should not see a vertical scrollbar.</p>

<div id="outer">
  <div id="middle">
    <div id="inner">
      hello
    </div>
  </div>
</div>

<div id="outer2">
  <div id="middle2">
    <div id="inner2">
      hello
    </div>
  </div>
</div>