JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" href="CSS/style.css">
    <link rel="preconnect" href="https://fonts.gstatic.com">
    <link rel="preconnect" href="https://fonts.gstatic.com">
    <link rel="preconnect" href="https://fonts.gstatic.com">
<link href="https://fonts.googleapis.com/css2?family=Open+Sans:wght@700&display=swap" rel="stylesheet">
    <title>Document</title>
</head>
<body>
    <div class="blockOverLay" id="Overlay">
        <p class="previewText" id="text">Нажми на меня</p>  
    </div>
    <script src="JS/script.js"></script>
</body>
</html>

CSS

* {
    margin: 0;
    padding: 0;
}

body {
    background-color: #FBD2B3;
}

.blockOverLay {
    position: fixed;
    background-color: black;
    width: 100%;
    height: 100%;
    z-index: 10;
    opacity: 1;
}
.blockOverLayActive {
    opacity: 0;
    transition: 3s;
}

.previewText {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
    text-align: center;
    font-size: 80px;
    color: white;
    font-family: 'Open Sans', sans-serif;
    opacity: 1;
}
.previewTextActive {
    opacity: 0;
    transition: 5s;
}

JavaScript

let inputView = document.getElementById("input1").value;
let inputResult = document.getElementById("input2").value;

let result = document.getElementById("result");

let previewText = document.getElementById("text");
let overlay = document.getElementById("Overlay");

window.onload = function() {
    previewText.classList.toggle("previewTextActive");
}