Javascript example

HTML

<div id="popUpDiv" class="popup" style="background: red; border-color: red;">
    <button class="btn" onclick="myFunction()">X</button>
    <p class="para">University</p>

</div>

CSS

.popup {
    margin: 10px;
    padding: 5px;
    position: relative;
    width:50%;
    
}
.popup:after {
    content: "";
    position: absolute;
   top: 100%;
   left: 20px;
   border-top: 20px solid blue;
   border-top-color: inherit; 
   border-left: 20px solid transparent;
   border-right: 20px solid transparent; 
}
.btn{
    
    float:right;
   
}
.para
{
   width:30%;
margin-left:30px;    
}

JavaScript

function myFunction()
{
document.getElementById("popUpDiv").style.display = "none";
}