bootstrap v4 vertical align code example

Example 1: centralize div bootstrap

<div class="row align-items-center justify-content-center">
    <div class="col">This will be centered vertically and horizontally</div>
</div>

Example 2: bootstrap table text vertical align center

/* Based on what you have provided your CSS selector is not specific enough to 
override the CSS rules defined by Bootstrap.

Try this:
*/

.table > tbody > tr > td {
     vertical-align: middle;
}

/*
In Boostrap 4, this can be achieved with the .align-middle Vertical 
Alignment utility class.
*/
<td class="align-middle">Text</td>