JSFiddle - React, Tailwind, and code Playground

HTML

<div class="uprava">
    <input id="inputBox" type="textarea" name="obsah" value="<?php echo $obsah; ?>"/>
</div>

CSS

#inputBox
    height: 184px;
    font-size: 16px;
    width:auto;
    min-width: 100%;
    margin-bottom: 10px;
    -webkit-appearance: none;
    background: #fff;
    border: 1px solid #d9d9d9;
    border-top: 1px solid #c0c0c0;
    padding: 0 8px;
    box-sizing: border-box;
    -moz-box-sizing: border-box;
}

JavaScript

document.getElementById("inputBox").style.whiteSpace = "nowrap";