آموزش ساخت AlertBox با css و html و JS

<div class="Alert">

  <span class="CloseButton" onclick="hide(this.parentElement)">&times;</span> 

  Alert Box Demo

</div>

.Alert {

    padding: 20px;

    background-color: #5C6BC0;

    color: white;

    margin-bottom: 15px;

}

.CloseButton {

    margin-left: 15px;

    color: white;

    font-weight: bold;

    float: right;

    font-size: 22px;

    line-height: 20px;

    cursor: pointer;

    transition: 0.3s;

}

.closebtn:hover {

    color: #000000;

}

.close{

display:none;

}

 function hide(button){

   button.parentElement.setAttribute("class", "close");

}