{
      font: 20px/1 Ahem;
  }
  @font-face {
      font-family: operators;
      src: url("/fonts/math/operators.woff");
  }
  mo {
      font-family: operators;
  }
</style>
</head>
<body>
  <p>Test passes if you see a green square.</p>
  <div style="background: green; color: red; width: 200px; height: 200px;">
    <math>
      <!-- unstretched operators -->
      <mo style="visibility: hidden">⥯</mo>
      <mo style="visibility: hidden">+</mo>
      <mo style="visibility: hidden">-</mo>
    </math>
   