JSFiddle - React, Tailwind, and code Playground

HTML

<div id="outer">
    <button>speichern</button>
    <div id="inner">TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>TEXT
        <br>
    </div>
</div>

CSS

#outer {
    height: 200px;
    background-color: red;
    position:relative;
}
#inner {
    position:absolute;
    top:0;
    left:0;
    bottom:0;
    right:0;
    overflow:auto;
}
button {
    position: absolute;
    bottom:0;
    z-index:1;
}