JSFiddle - React, Tailwind, and code Playground

HTML

<div class="cf-full">
    <input id="a" />
    <label class="helptext">Label</label>
</div>

CSS

.cf-full input,
.cf-full label{
    float:left;
}
@media all and (max-width: 300px){
    .cf-full input,
    .cf-full label{
        float:right;
    }
}