le(element).marginLeft,
                    getComputedStyle(ref).marginLeft);
    } finally {
      element.style = '';
      ref.style = '';
    }
  }

  test(() => {
    try {
      c1.className = 'inline w500'; // Selected by nothing.
      c2.className = 'size h400 w300'; // Selected by cqh, cqb.
      c3.className = 'inline w100'; // Selected by cqw, cqi.
      assert_unit_equals(child, '10cqw', '10px');
      assert_unit_equals(child, '10cqi', '10px');
      assert_unit_equals(child, '10cqh', '40px')