指定导航使用向上箭头和向下箭头导航键 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <style>
    button {
      position: absolute;
    }

    button#b1 {
      top: 20%;
      left: 25%;
      nav-index: 1;
      nav-right: #b2;
      nav-left: #b4;
      nav-down: #b2;
      nav-up: #b4;
    }

    button#b2 {
      top: 40%;
      left: 50%;
      nav-index: 2;
      nav-right: #b3;
      nav-left: #b1;
      nav-down: #b3;
      nav-up: #b1;
    }

    button#b3 {
      top: 70%;
      left: 25%;
      nav-index: 3;
      nav-right: #b4;
      nav-left: #b2;
      nav-down: #b4;
      nav-up: #b2;
    }

    button#b4 {
      top: 40%;
      left: 0%;
      nav-index: 4;
      nav-right: #b1;
      nav-left: #b3;
      nav-down: #b1;
      nav-up: #b3;
    }
  </style>
</head>
<body>

  <button id="b1">按钮1</button>
  <button id="b2">按钮2</button>
  <button id="b3">按钮3</button>
  <button id="b4">按钮4</button>

  <p><b>注释：</b>目前只有 Opera 支持 nav-* 属性。当您使用方向键导航时，请同时按下 Shift 键。</p>

</body>
</html>
        