JSFiddle - React, Tailwind, and code Playground

HTML

<div id="modal">
    <h2>CONTATO</h2>
    <div id="form">
        <form id="form-contato" action="contato/send" method="post" name="contato" >
            <label for="txtTeste" >Teste:</label>
            <input is="txtTeste" type="text" />
        </form>
    <div>
</div>

CSS

#modal {
    position: absolute;
    background-color: gainsboro;
    top: 0px;
    bottom: 0px;
    left: 0px;
    right: 0px;
    z-index: 5;
    opacity: 0.4;
    filter: alpha(opacity=40);
}

#form {
    width: 100%;
    height: 100px;
    background-color: white;
    box-shadow: 0px 0px 10px black;
    position: absolute;
    margin: auto;    
    
    top: 0px;
    bottom: 0px;
    left: 0px;
    right: 0px;
    z-index: 10;
}