JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block">
    <div class="centered">
        <div><input type="submit" value="ABC"/></div>
        <div><input type="submit" value="ABC"/></div>
        <div><input type="submit" value="ABC"/></div>
    </div>
</div>

CSS

/* Can be any width and height */
.block {
    height:500px;
    text-align: center;
}

/* The ghost, nudged to maintain perfect centering */
.block:before {
    content:'';
    display: inline-block;
    height: 100%;
    vertical-align: middle;
    margin-right: -0.25em; /* Adjusts for spacing */
}

/* The element to be centered, can be any width or height */
.centered {
    display: inline-block;
    vertical-align: middle;
    width: 300px;
}