CODE:

<style>
*{
    margin:0; padding:0;
    box-sizing: border-box;
    outline: none; border:none;
    transition: all .2s linear;
}
.kv-container{
    min-height: 100vh;
    background:#eee;
    display: flex;
    align-items: center;
    justify-content: center;
}
.btn{
    color:#fff;
    background:#ff6933;
    box-shadow: 0 5px 10px rgba(0,0,0,.3);
    border-radius: 5px;
    cursor: pointer;
}
.btn:hover{
    background:#ff4400;
}
.btn:active{
    transform:scale(.90);
}
#button{
    font-size: 25px;
    height:60px;
    width:250px;
}

.popup-container{
    position: fixed;
    top:-120%; left:0;
    z-index: 1000;
    background:rgba(0,0,0,.3);
    display: flex;
    align-items: center;
    justify-content: center;
    height:100%;
    width:100%;
}
.popup-container.toggle{
    top:0%;
}

.popup-container .popup{
    background:#fff;
    text-align: center;
    margin:10px;
    padding:10px;
    box-shadow: 0 5px 10px rgba(0,0,0,.5);
    border-radius: 5px;
    position: relative;
}
.popup-container .popup h3{
    color:#444;
    padding:20px 40px;
    font-size: 25px;
}
.popup-container .popup .btn{
    margin:30px;
    font-size: 20px;
    height:40px;
    width: 150px;
}
.popup-container .popup input[type="radio"]{
    display: none;
}
.popup-container .popup .icons{
    padding:10px;
}
.popup-container .popup .icons label{
    font-size: 50px;
    cursor: pointer;
    opacity: .4;
}
.popup-container .popup .icons:hover label{
    opacity: .2;
}

.popup-container .popup #btn1:checked ~ .icons label:nth-child(1),
.popup-container .popup #btn2:checked ~ .icons label:nth-child(2),
.popup-container .popup #btn3:checked ~ .icons label:nth-child(3),
.popup-container .popup #btn4:checked ~ .icons label:nth-child(4),
.popup-container .popup #btn5:checked ~ .icons label:nth-child(5),
.popup-container .popup .icons label:hover{
    opacity: 1;
    font-size: 60px;
}

.popup-container .popup #close{
    position: absolute;
    top:-15px; right:-15px;
    border-radius: 50%;
    border:4px solid #ff6933;
    height:40px;
    width:40px;
    line-height: 35px;
    cursor: pointer;
    background:#333;
    color:#fff;
    font-size: 20px;
}

.popup-container .popup #close:hover{
    transform: rotate(90deg);
}
</style>

  
<div class="kv-container">
    <button onclick="toggle()"  id="button" class="btn">popup</button>
</div>

<div class="popup-container">
    <div class="popup">
        <p>Warning: When you delete the domain name from your<br>
             hosting account, any associated email addresses that<br>
              you created in the cPanel dashboard will also be removed.</p>
        <input type="submit" value="submit" class="btn">
        <div onclick="toggle()" id="close">✖</div>
    </div>
</div>

<script>
function toggle(){
 let toggle = document.querySelector('.popup-container')
 toggle.classList.toggle('toggle');
}
</script>

sabe.io/tutorials/how-to-create-modal-popup-box