JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div id="selectModel" class="admin_dropdown">
         <h5 class="admin_caption">Wählen sie das anzuzeigende Model</h5>

        <select id="selectModelDDL" onchange="createTable(this);"></select>
    </div>

CSS

div.container {
    margin: 15px;
    clear: both;
    /*        float: left;*/
}
div.admin_dropdown {
    float: left;
    padding: 10px;
    width: 300px;
    border: 1px solid black;
    border-radius: 15px;
}
h5.admin_caption {
    width: 300px;
    margin-top: -20px;
    margin-left: auto;
    margin-right: auto;
    background: white;
}