<slot>：Web 组件插槽元素

<template id="element-details-template">
  <style>
    details {
      font-family: "Open Sans Light", Helvetica, Arial, sans-serif;
    }
    .name {
      font-weight: bold;
      color: #217ac0;
      font-size: 120%;
    }
    h4 {
      margin: 10px 0 -8px 0;
      background: #217ac0;
      color: white;
      padding: 2px 6px;
      border: 1px solid #cee9f9;
      border-radius: 4px;
    }
    .attributes {
      margin-left: 22px;
      font-size: 90%;
    }
    .attributes p {
      margin-left: 16px;
      font-style: italic;
    }
  </style>
  <details>
    <summary>
      <code class="name">
        &lt;<slot name="element-name">需要名称</slot>&gt;
      </code>
      <span class="desc"><slot name="description">需要描述</slot></span>
    </summary>
    <div class="attributes">
      <h4>属性</h4>
      <slot name="attributes"><p>无</p></slot>
    </div>
  </details>
  <hr />
</template>