JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="background">This is a test</div>
    <textarea>This is a test</textarea>
</div>
<div class="container fixed">
    <div class="background">This is a test</div>
    <textarea>This is a test</textarea>
</div>

CSS

.container {
    border: 1px solid #cdcdcd;
    background: #f0f0f0;
    width: 400px;
    height: 50px;
    position: relative;
    margin: 24px 0;
}

.background {
    position: absolute;
    top: 0;
    right: 0;
    bottom: 0;
    left: 0;
    color: #f00;
}

textarea {
    width: 100%;
    height: 100%;
    box-sizing: border-box;
    background: transparent;
    border: 0;
    position: relative;
    z-index: 2;
}

.background, textarea {
    padding: 12px 5%;
    font: 12px/1.6 Helvetica, Arial, sans-serif;
}

.container.fixed .background,
.container.fixed textarea {
    padding: 12px 12px;
}