基础表格

<div class="container mt-3">
  <h2>基础表格</h2>
  <p>.table 类来设置基础表格的样式:</p>            
  <table class="table">
    <thead>
      <tr>
        <th>Firstname</th>
        <th>Lastname</th>
        <th>Email</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td>John</td>
        <td>Doe</td>
        <td><div class="container mt-3"