html实例之给table的tbody设置垂直滚动条但thead固定不动

html代码：

<table>
  <thead>
    <tr>
      <th>Name</th>
      <th>Color</th>
      <th>De ion</th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>Apple</td>
      <td>Red</td>
      <td>These are red.</td>
    </tr>
    <tr>
      <td>Pear</td>
      <td>Green</td>
      <td>These are green.</td>
    </tr>
    <tr>
      <td>Grape</td>
      <td>Purple / Green</td>
      <td>These are purple and green.</td>
    </tr>
    <tr>
      <td>Orange</td>
      <td>Orange</td>
      <td>These are orange.</td>
    </tr>
    <tr>
      <td>Banana</td>
      <td>Yellow</td>
      <td>These are yellow.</td>
    </tr>
    <tr>
      <td>Kiwi</td>
      <td>Green</td>
      <td>These are green.</td>
    </tr>
  </tbody>
</table>

css代码：

table {
  width: 100%;
  text-align: left;
  min-width: 610px;
}
tr {
  height: 30px;
  padding-top: 10px
}
tbody { 
  height: 150px; 
  overflow-y: auto;
  overflow-x: hidden;
}
th,td,tr,thead,tbody { display: block; }
td,th { float: left; }
td:nth-child(1),
th:nth-child(1) {
  width: 20%;
}
td:nth-child(2),
th:nth-child(2) {
  width: 20%;
  float: left;
}
td:nth-child(3),
th:nth-child(3) {
  width: 59%;
  float: left;
}
/* some colors */
thead {
  background-color: #333333;
  color: #fdfdfd;
}
table tbody tr:nth-child(even) {
  background-color: #dddddd;
}

运行结果：在线运行