在保持宽度不变的同时，在IE11中固定表头

<div class="table-container">
  <table>
    <thead>
      <tr>
        <th>表头1</th>
        <th>表头2</th>
        <th>表头3</th>
      </tr>
    </thead>
    <tbody>
      <!-- 表格内容 -->
    </tbody>
  </table>
</div>

.table-container {
  overflow: auto;
  height: 300px; /* 设置表格容器的高度，使其可以滚动 */
}

table {
  width: 100%;
  border-collapse: collapse;
}

th, td {
  padding: 8px;
  border: 1px solid #ccc;
}

thead {
  background-color: #f9f9f9;
}

window.addEventListener('DOMContentLoaded', function() {
  var tableContainer = document.querySelector('.table-container');
  var tableHead = document.querySelector('thead');
  
  // 计算表头的位置
  function fixTableHead() {
    var rect = tableContainer.getBoundingClientRect();
    var top = rect.top;
    var left = rect.left;
    
    tableHead.style.position = 'fixed';
    tableHead.style.top = top + 'px';
    tableHead.style.left = left + 'px';
    tableHead.style.width = tableContainer.offsetWidth + 'px';
  }
  
  // 监听滚动事件，更新表头的位置
  tableContainer.addEventListener('scroll', function() {
    fixTableHead();
  });
  
  // 初始化时固定表头
  fixTableHead();
});