Please note that vertical-align only affects inline, inline-block, inline-table, and table cell elements.
Choose from vertical-align= baseline, top, middle, bottom, text-bottom, and text-top as needed. 
 To vertically center non-inline content (like <div>s and more), use our  flex box utilities . 
With inline elements:
 baseline  top  middle  bottom  text-top  text-bottom 
vue
<template>
 <b-span vertical-align="baseline">
  baseline
 </b-span>
 <b-span vertical-align="top">
  top
 </b-span>
 <b-span vertical-align="middle">
  middle
 </b-span>
 <b-span vertical-align="bottom">
  bottom
 </b-span>
 <b-span vertical-align="text-top">
  text-top
 </b-span>
 <b-span vertical-align="text-bottom">
  text-bottom
 </b-span>
</template>
With table cells:
 baseline  top  middle  bottom  text-top  text-bottom 
| baseline | top | middle | bottom | text-top | text-bottom | 
vue
<template>
 <b-span vertical-align="baseline">
  baseline
 </b-span>
 <b-span vertical-align="top">
  top
 </b-span>
 <b-span vertical-align="middle">
  middle
 </b-span>
 <b-span vertical-align="bottom">
  bottom
 </b-span>
 <b-span vertical-align="text-top">
  text-top
 </b-span>
 <b-span vertical-align="text-bottom">
  text-bottom
 </b-span>
 <b-table style="height: 100px">
  <b-tbody>
   <b-tr>
    <b-td vertical-align="baseline">
     baseline
    </b-td>
    <b-td vertical-align="top">
     top
    </b-td>
    <b-td vertical-align="middle">
     middle
    </b-td>
    <b-td vertical-align="bottom">
     bottom
    </b-td>
    <b-td vertical-align="text-top">
     text-top
    </b-td>
    <b-td vertical-align="text-bottom">
     text-bottom
    </b-td>
   </b-tr>
  </b-tbody>
 </b-table>
</template>