JSFiddle - React, Tailwind, and code Playground

HTML

<div class="box">
    <label for="" style="width: 100px;">Label</label>
    <input type="text" value="input">
</div>
<div class="box">
    <label for="" style="width: 60px;">Label</label>
    <input type="text" value="input">
</div>

CSS

.box {
    width: 500px;
    margin-bottom: 10px;
    display: table;
}
label,
input{
    display: table-cell;
}
input {
    width: 100%;
    margin-left: 10px;
}
label {
    background-color: #ccc;
}