CSS vertical-align, how can I remove the little spacing below the text?

问题

I have this code. Despite of being inside a td, and having specified this CSS:

.day {
    text-align: right;
    padding: 5px;
    vertical-align: middle;
    border: 1px solid black;
}

.day--hole {
    color: lightgray;
}

.day--today {
    background: pink;
}

<table>
  <tbody>
    <tr>
      <td class="day day--hole">30</td>
      <td class="day day--hole">31</td>
      <td class="day">1</td>
      <td class="day">2</td>
      <td class="day">3</td>
      <td class="day">4</td>
      <td class="day">5</td>
    </tr>
    <tr>
      <td class="day">6</td>
      <td class="day">7</td>
      <td class="day">8</td>
      <td class="day">9</td>
      <td class="day">10</td>
      <td class="day">11</td>
      <td class="day">12</td>
    </tr>
    <tr>
      <td class="day">13</td>
      <td class="day">14</td>
      <td class="day">15</td>
      <td class="day">16</td>
      <td class="day">17</td>
      <td class="day">18</td>
      <td class="day">19</td>
    </tr>
    <tr>
      <td class="day">20</td>
      <td class="day day--today">21</td>
      <td class="day">22</td>
      <td class="day">23</td>
      <td class="day">24</td>
      <td class="day">25</td>
      <td class="day">26</td>
    </tr>
    <tr>
      <td class="day">27</td>
      <td class="day">28</td>
      <td class="day">29</td>
      <td class="day">30</td>
      <td class="day">31</td>
      <td class="day day--hole">1</td>
      <td class="day day--hole">2</td>
    </tr>
  </tbody>
</table>

There's a visible gap between the position where the text should be centered and the current position of the text. It looks "upper" than it should and not totally centered. Why does this happen and how can I solve it without recurring to change the HTML or use flexbox?

回答1:

As an example I made the height higher than needed. But give the example below a try. The height and line-height should be equal to center the text.

let height = document.getElementById('height');
let days = Array.from( document.querySelectorAll('.day') );

height.addEventListener('input', () => {
  days.forEach( day => {
    day.style.setProperty( '--height', `${height.value}px` );
  });
});

.day {
    text-align: right;
    padding: 5px;
    height: var(--height);
    line-height: var(--height);
    border: 1px solid black;
}

.day--hole {
    color: lightgray;
}

.day--today {
    background: pink;
}

:root {
  --height: 40px;
}

<form>
  <label for="height">Height (play with it to say that the text remains centered)</label>
  <input type="number" id="height" min="1" value="40">
</form>

<table>
  <tbody>
    <tr>
      <td class="day day--hole">30</td>
      <td class="day day--hole">31</td>
      <td class="day">1</td>
      <td class="day">2</td>
      <td class="day">3</td>
      <td class="day">4</td>
      <td class="day">5</td>
    </tr>
    <tr>
      <td class="day">6</td>
      <td class="day">7</td>
      <td class="day">8</td>
      <td class="day">9</td>
      <td class="day">10</td>
      <td class="day">11</td>
      <td class="day">12</td>
    </tr>
    <tr>
      <td class="day">13</td>
      <td class="day">14</td>
      <td class="day">15</td>
      <td class="day">16</td>
      <td class="day">17</td>
      <td class="day">18</td>
      <td class="day">19</td>
    </tr>
    <tr>
      <td class="day">20</td>
      <td class="day day--today">21</td>
      <td class="day">22</td>
      <td class="day">23</td>
      <td class="day">24</td>
      <td class="day">25</td>
      <td class="day">26</td>
    </tr>
    <tr>
      <td class="day">27</td>
      <td class="day">28</td>
      <td class="day">29</td>
      <td class="day">30</td>
      <td class="day">31</td>
      <td class="day day--hole">1</td>
      <td class="day day--hole">2</td>
    </tr>
  </tbody>
</table>

回答2:

That's because these numbers technically are text, and text - when using letters - has letters like g, j, p etc. which extend below the baseline. That's part of the line-height, and the vertical centering centers that line-height, regardless if there are letters like g, j, p in the text or not. So it looks a bit vertically offset as you describe it.

To compensate that, you could apply a vertical offset, as I did it in the first and last row of this snippet, using a wrapper for the numbers and applying position: relative and transform: translateY(1px); (or any value you like) to it:

.day {
    text-align: right;
    padding: 5px;
    vertical-align: middle;
    border: 1px solid black;
}

.day--hole {
    color: lightgray;
}

.day--today {
    background: pink;
}
.offset {
position: relative;
transform: translateY(1px);
}

<table>
  <tbody>
    <tr>
      <td class="day day--hole"><div class="offset">30</div></td>
      <td class="day day--hole"><div class="offset">31</div></td>
      <td class="day"><div class="offset">1</div></td>
      <td class="day"><div class="offset">2</div></td>
      <td class="day"><div class="offset">3</div></td>
      <td class="day"><div class="offset">4</div></td>
      <td class="day"><div class="offset">5</div></td>
    </tr>
    <tr>
      <td class="day">6</td>
      <td class="day">7</td>
      <td class="day">8</td>
      <td class="day">9</td>
      <td class="day">10</td>
      <td class="day">11</td>
      <td class="day">12</td>
    </tr>
    <tr>
      <td class="day">13</td>
      <td class="day">14</td>
      <td class="day">15</td>
      <td class="day">16</td>
      <td class="day">17</td>
      <td class="day">18</td>
      <td class="day">19</td>
    </tr>
    <tr>
      <td class="day">20</td>
      <td class="day day--today">21</td>
      <td class="day">22</td>
      <td class="day">23</td>
      <td class="day">24</td>
      <td class="day">25</td>
      <td class="day">26</td>
    </tr>
    <tr>
      <td class="day"><div class="offset">27</div></td>
      <td class="day"><div class="offset">28</div></td>
      <td class="day"><div class="offset">29</div></td>
      <td class="day"><div class="offset">30</div></td>
      <td class="day"><div class="offset">31</div></td>
      <td class="day day--hole"><div class="offset">1</div></td>
      <td class="day day--hole"><div class="offset">2</div></td>
    </tr>
  </tbody>
</table>

回答3:

.day has text-align: right; on it. Set that to text-align: center;

来源：https://stackoverflow.com/questions/51955295/css-vertical-align-how-can-i-remove-the-little-spacing-below-the-text

标签

css

css3

vertical-alignment