应用bootstrap，然后表格单元格崩溃

Question

我在我的页面添加了bootstrap来解决另一个问题，然后我注意到我在另一个地方的表格单元格全部崩溃了：

如何让单元格自动调整大小？我已经看到有关更改单元格宽度的帖子，但我需要将其高度更改回其预引导设置。

这是我的代码：

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.countdown_table {
  margin-left: auto;
  margin-right: auto;
  margin-top: 30px;
}

.countdown_table tr td {
  font-family: 'proxima-nova', sans-serif;
  padding-right: 20px;
  color: white;
  text-align: center;
}

.units {
  font-weight: 100;
  text-transform: uppercase;
  text-align: center;
}

.numbers {
  font-size: 700%;
  font-weight: 100;
  letter-spacing: 0;
  text-align: center;
  background: #e18b35 !important;
  font-family: 'proxima-nova', sans-serif;
  color: white;
}

#secondElem {
  width: 97px !important;
}

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<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" integrity="sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u" crossorigin="anonymous">
<table class="countdown_table" border="1">
  <tr>
    <td class="numbers" id="dayElem">04</td>
    <td class="numbers">:</td>
    <td class="numbers" id="hourElem">02</td>
    <td class="numbers">:</td>
    <td class="numbers" id="minuteElem">47</td>
    <td class="numbers">:</td>
    <td class="numbers" id="secondElem">04</td>
  </tr>
  <tr class="units">
    <td>days</td>
    <td></td>
    <td>hours</td>
    <td></td>
    <td>minutes</td>
    <td></td>
    <td>seconds</td>
  </tr>
</table>

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