您可以添加

.table {
  border-collapse: separate;
}

但不幸的是，它看起来很糟糕，一个更好的解决方案是使用伪元素添加一个变通方案。

th:after,
th:before {
  content: '';
  position: absolute;
  left: 0;
  width: 100%;
}

th:before {
  top: -1px;
  border-top: 1px solid red;
}

th:after {
  bottom: -1px;
  border-bottom: 2px solid red;
}

第一次
第二种解决方案

.table {
  border-collapse: collapse;
}

.table-sticky thead th {
  position: -webkit-sticky;
  position: sticky;
  top: 0;
  z-index: 2;
  box-shadow: inset 0 1px 0 red, inset 0 -2px 0 red;
}

您可以添加

.table {
  border-collapse: separate;
  border-spacing: 0;
}

不要使用border-collapse，按如下方式绘制直线：

td, th {
    border-bottom: 1px solid grey;
    border-right: 1px solid grey;
}

table {
    border-spacing: 0px;
    border-left: 1px solid grey
}

th {
    background-color:#c5e8ec;
    position: sticky;
    position: -webkit-sticky;
    border-top: 1px solid grey;
    top:0;
}

Another working solution（在最新的Chrome和FF上测试）-使用div Package th/td内容，并使用这些div边框而不是单元格边框。

<div class="wrapper">
  <table>
  <thead>
    <tr>
      <th>
        <div class="cell">head1</div>
      </th>
      <th>
        <div class="cell">head2</div>
      </th>
      <th>
        <div class="cell">head3</div>
      </th>
      <th>
        <div class="cell">head4</div>
      </th>
      <th>
        <div class="cell">head5</div>
      </th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
    </tr>
    <tr>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
    </tr>
    <tr>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
      <td>
        <div class="cell">1</div>
      </td>
    </tr>
  </tbody>
</table>
</div>

table {
  border-collapse: collapse;
  table-layout: fixed;
  width: 500px;
}

.wrapper {
  height: 150px;
  overflow: auto;
}

td, th {
  width: 150px;
  height: 50px;
  text-align: center;
  font-size: 32px;
  padding: 0;
}

th {
  position: sticky;
  top: 0;
  left: 0;
  background-color: #fff;
}

.cell {
  border: 1px solid black;
  height: 100%;
}

td .cell {
  border-top: none;
  border-left: none;
}

th .cell {
  border-left: none;
}

td:first-child .cell,
th:first-child .cell {
  border-left: 1px solid black;
}