JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block aligned">
    <div class="child">
        I'm centred and alone.
    </div>
</div>
<div class="fixed aligned">
    <div class="child">
        I'm centred.
    </div>
    <div class="child another">
        Me too.
    </div>
</div>

CSS

.fixed {
    position: fixed; width: 100%;
}
.aligned {
    text-align: center;
}
.child {
    display: inline-block; 
    *display: inline; zoom: 1; /* http://stackoverflow.com/a/5838575/1129420 */
}

.another {
    background: #dfd;
    padding: 1em;
}
.block {
    margin-top: 5em;
    background: #fee;
}