JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="center-1">
        Center Me!
    </div>
</div>

<div class="container">
    <div class="center-2">
        Center Me!
    </div>
</div>

<div class="container">
    <div class="center-3">
        Center Me!
    </div>
</div>
<div class="container">
    <div class="center-4">
        Center Me!
    </div>
</div>

CSS

.container{
    height:300px;
    width:500px;
    margin:20px;
    border:1px solid black;
    position:relative;
    display: table;
}
.center-1{
    position:absolute;
    top:50%;
    width:100%;
    height:1em;
    margin-top:-.5em;
    text-align:center;
}

.center-2{
    width:100%;
    height:100%;
    display: table-cell;
    vertical-align: middle;
    text-align:center;
}
.center-3{
    width:100%;
    line-height: 300px;
    text-align:center;
}
.center-4{
    margin-top:29%;  
    width:100%;
    text-align:center;
}