<!DOCTYPE html>
<title>calc-size() on flex-basis</title>
<link rel="help" href="https://drafts.csswg.org/css-values-5/#calc-size">
<link rel="help" href="https://drafts.csswg.org/css-flexbox/#flex-basis-property">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="stylesheet" href="/fonts/ahem.css">
<style>
  #container {
    display: flex;
    flex-direction: row;
    font-family: 'Ahem';
    font-size: 20px;
    width: 500px;
  }
  #target 