JSFiddle - React, Tailwind, and code Playground

HTML

<html>

<head>
    <link rel="stylesheet" href="style.css">
</head>

<body>



    <div class="notepad">
        <div class="add-button">
            <input type="text" class="topic" value="Заголовок">
            <input type="text" class="description" value="Описание">
            Добавить
        </div>
    </div>


    <script src="script.js"></script>
</body>

</html>

CSS

* {
    margin: 0px; padding: 0px; color: white; text-align: center;
}

.notepad {
    width: 500px;
    height: 800px;
    background-color: #8FC2E9;
    margin: 50px auto;
    position: relative;
}

.note {
    width: 450px;
    height: 50px;
    background-color: #3F92D2;
    margin: 20px auto;
    position: relative;
}

.note-description {
    width: 450px;
    height: 150px;
    background-color: #66A3D2;
    margin: auto;
    position: absolute;
    top: 100%;
    z-index: 1;
}

.delete-button {
    width: 10px;
    height: 10px;
    background-color: #BF3030;
    position: absolute;
    top: 10px; right: 10px;
    border-radius: 100%;
    z-index: 1;
}

.hide {
    display: none;
}

.add-button {
    width: 450px;
    height: 100px;
    background-color: #215C89;
    margin: auto;
    position: absolute;
    bottom: 20px; left: 25px;
}

.topic {
    width: 100%;
    height: 25px;
    border: none;
    background-color: #A7CCE9;
}

.description {
    width: 100%;
    height: 50px;
    border: none;
    background-color: rgb(192, 214, 231);
}

JavaScript

var notepad = document.querySelector('.notepad');
var topic = document.querySelector('.topic');
var description = document.querySelector('.description');
var noteQty = 0;

notepad.addEventListener('click', function(event) {
    console.log(event.target);

    if (event.target.classList == 'add-button' && noteQty != 9) {

        var note = document.createElement('div');
        note.classList.add('note');
        note.textContent = topic.value;
        topic.value = '';
        
        var noteDescription = document.createElement('div');
        noteDescription.classList.add('note-description', 'hide');
        noteDescription.textContent = description.value;
        description.value = '';

        var deleteButton = document.createElement('div');
        deleteButton.classList.add('delete-button', 'hide')
        deleteButton.addEventListener('click', function() {
            note.style.display = 'none';
            noteQty--;
        })

        note.insertAdjacentElement('afterbegin', noteDescription);
        note.insertAdjacentElement('afterbegin', deleteButton);
        note.addEventListener('mouseenter', function() {
            noteDescription.classList.remove('hide');
            deleteButton.classList.remove('hide');
        })
        note.addEventListener('mouseleave', function() {
            noteDescription.classList.add('hide');
            deleteButton.classList.add('hide');
        })

        notepad.insertAdjacentElement('afterbegin', note);
        noteQty++;

    }
})