无法让单选按钮样式在 plunker 中工作

我试图让这里找到的倾斜单选按钮样式（https://codepen.io/anon/pen/yXNopJ）在我的项目中工作。从视觉上看，它看起来不错，但在点击时没有做任何事情。所以为了调试，我想我会把它放在 plunker 中并在一个孤立的区域玩它。但是，当我将 html 和 css 复制并粘贴到 Plunker 中时，视觉效果不起作用。谁能看出为什么视觉效果在 plunker 中不起作用但在 codepen 中起作用？

http://plnkr.co/edit/IPiDZdLS51UzAwUcQZHp?p=preview

HTML

<h2>Toggle 'em</h2>
<ul class="tg-list">
  <li class="tg-list-item">
    <h4>Light</h4>
    <input class="tgl tgl-light" id="cb1" type="checkbox"/>
    <label class="tgl-btn" for="cb1"></label>
  </li>
  <li class="tg-list-item">
    <h4>iOS</h4>
    <input class="tgl tgl-ios" id="cb2" type="checkbox"/>
    <label class="tgl-btn" for="cb2"></label>
  </li>
  <li class="tg-list-item">
    <h4>Skewed</h4>
    <input class="tgl tgl-skewed" id="cb3" type="checkbox"/>
    <label class="tgl-btn" data-tg-off="OFF" data-tg-on="ON" for="cb3"></label>
  </li>
  <li class="tg-list-item">
    <h4>Flat</h4>
    <input class="tgl tgl-flat" id="cb4" type="checkbox"/>
    <label class="tgl-btn" for="cb4"></label>
  </li>
  <li class="tg-list-item">
    <h4>Flip</h4>
    <input class="tgl tgl-flip" id="cb5" type="checkbox"/>
    <label class="tgl-btn" data-tg-off="Nope" data-tg-on="Yeah!" for="cb5"></label>
  </li>
</ul>

CSS

html, body {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  min-height: 100%;
  -webkit-box-pack: center;
      -ms-flex-pack: center;
          justify-content: center;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
  -webkit-box-orient: vertical;
  -webkit-box-direction: normal;
      -ms-flex-direction: column;
          flex-direction: column;
  font-family: sans-serif;
}

ul, li {
  list-style: none;
  margin: 0;
  padding: 0;
}

.tg-list {
  text-align: center;
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -webkit-box-align: center;
      -ms-flex-align: center;
          align-items: center;
}

.tg-list-item {
  margin: 0 2em;
}

h2 {
  color: #777;
}

h4 {
  color: #999;
}

.tgl {
  display: none;
}
.tgl, .tgl:after, .tgl:before, .tgl *, .tgl *:after, .tgl *:before, .tgl + .tgl-btn {
  box-sizing: border-box;
}
.tgl::-moz-selection, .tgl:after::-moz-selection, .tgl:before::-moz-selection, .tgl *::-moz-selection, .tgl *:after::-moz-selection, .tgl *:before::-moz-selection, .tgl + .tgl-btn::-moz-selection {
  background: none;
}
.tgl::selection, .tgl:after::selection, .tgl:before::selection, .tgl *::selection, .tgl *:after::selection, .tgl *:before::selection, .tgl + .tgl-btn::selection {
  background: none;
}
.tgl + .tgl-btn {
  outline: 0;
  display: block;
  width: 4em;
  height: 2em;
  position: relative;
  cursor: pointer;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none;
}
.tgl + .tgl-btn:after, .tgl + .tgl-btn:before {
  position: relative;
  display: block;
  content: "";
  width: 50%;
  height: 100%;
}
.tgl + .tgl-btn:after {
  left: 0;
}
.tgl + .tgl-btn:before {
  display: none;
}
.tgl:checked + .tgl-btn:after {
  left: 50%;
}

.tgl-light + .tgl-btn {
  background: #f0f0f0;
  border-radius: 2em;
  padding: 2px;
  -webkit-transition: all .4s ease;
  transition: all .4s ease;
}
.tgl-light + .tgl-btn:after {
  border-radius: 50%;
  background: #fff;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
}
.tgl-light:checked + .tgl-btn {
  background: #9FD6AE;
}

.tgl-ios + .tgl-btn {
  background: #fbfbfb;
  border-radius: 2em;
  padding: 2px;
  -webkit-transition: all .4s ease;
  transition: all .4s ease;
  border: 1px solid #e8eae9;
}
.tgl-ios + .tgl-btn:after {
  border-radius: 2em;
  background: #fbfbfb;
  -webkit-transition: left 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275), padding 0.3s ease, margin 0.3s ease;
  transition: left 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275), padding 0.3s ease, margin 0.3s ease;
  box-shadow: 0 0 0 1px rgba(0, 0, 0, 0.1), 0 4px 0 rgba(0, 0, 0, 0.08);
}
.tgl-ios + .tgl-btn:hover:after {
  will-change: padding;
}
.tgl-ios + .tgl-btn:active {
  box-shadow: inset 0 0 0 2em #e8eae9;
}
.tgl-ios + .tgl-btn:active:after {
  padding-right: .8em;
}
.tgl-ios:checked + .tgl-btn {
  background: #86d993;
}
.tgl-ios:checked + .tgl-btn:active {
  box-shadow: none;
}
.tgl-ios:checked + .tgl-btn:active:after {
  margin-left: -.8em;
}

.tgl-skewed + .tgl-btn {
  overflow: hidden;
  -webkit-transform: skew(-10deg);
          transform: skew(-10deg);
  -webkit-backface-visibility: hidden;
          backface-visibility: hidden;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  font-family: sans-serif;
  background: #888;
}
.tgl-skewed + .tgl-btn:after, .tgl-skewed + .tgl-btn:before {
  -webkit-transform: skew(10deg);
          transform: skew(10deg);
  display: inline-block;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  width: 100%;
  text-align: center;
  position: absolute;
  line-height: 2em;
  font-weight: bold;
  color: #fff;
  text-shadow: 0 1px 0 rgba(0, 0, 0, 0.4);
}
.tgl-skewed + .tgl-btn:after {
  left: 100%;
  content: attr(data-tg-on);
}
.tgl-skewed + .tgl-btn:before {
  left: 0;
  content: attr(data-tg-off);
}
.tgl-skewed + .tgl-btn:active {
  background: #888;
}
.tgl-skewed + .tgl-btn:active:before {
  left: -10%;
}
.tgl-skewed:checked + .tgl-btn {
  background: #86d993;
}
.tgl-skewed:checked + .tgl-btn:before {
  left: -100%;
}
.tgl-skewed:checked + .tgl-btn:after {
  left: 0;
}
.tgl-skewed:checked + .tgl-btn:active:after {
  left: 10%;
}

.tgl-flat + .tgl-btn {
  padding: 2px;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  background: #fff;
  border: 4px solid #f2f2f2;
  border-radius: 2em;
}
.tgl-flat + .tgl-btn:after {
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  background: #f2f2f2;
  content: "";
  border-radius: 1em;
}
.tgl-flat:checked + .tgl-btn {
  border: 4px solid #7FC6A6;
}
.tgl-flat:checked + .tgl-btn:after {
  left: 50%;
  background: #7FC6A6;
}

.tgl-flip + .tgl-btn {
  padding: 2px;
  -webkit-transition: all .2s ease;
  transition: all .2s ease;
  font-family: sans-serif;
  -webkit-perspective: 100px;
          perspective: 100px;
}
.tgl-flip + .tgl-btn:after, .tgl-flip + .tgl-btn:before {
  display: inline-block;
  -webkit-transition: all .4s ease;
  transition: all .4s ease;
  width: 100%;
  text-align: center;
  position: absolute;
  line-height: 2em;
  font-weight: bold;
  color: #fff;
  position: absolute;
  top: 0;
  left: 0;
  -webkit-backface-visibility: hidden;
          backface-visibility: hidden;
  border-radius: 4px;
}
.tgl-flip + .tgl-btn:after {
  content: attr(data-tg-on);
  background: #02C66F;
  -webkit-transform: rotateY(-180deg);
          transform: rotateY(-180deg);
}
.tgl-flip + .tgl-btn:before {
  background: #FF3A19;
  content: attr(data-tg-off);
}
.tgl-flip + .tgl-btn:active:before {
  -webkit-transform: rotateY(-20deg);
          transform: rotateY(-20deg);
}
.tgl-flip:checked + .tgl-btn:before {
  -webkit-transform: rotateY(180deg);
          transform: rotateY(180deg);
}
.tgl-flip:checked + .tgl-btn:after {
  -webkit-transform: rotateY(0);
          transform: rotateY(0);
  left: 0;
  background: #7FC6A6;
}
.tgl-flip:checked + .tgl-btn:active:after {
  -webkit-transform: rotateY(20deg);
          transform: rotateY(20deg);
}