how to make a custom popup container like youtube - css

Question

I want make the popup windows like youtube share because its stick next to button. I tried bootstrap modal but it's popup in the middle of screen. When click youtube share button,pop up shows around button.
Does anyone know how to fix it?
HTML
<div class="box">
<a class="button" href="#popup1">share</a>
</div>
<div id="popup1" class="overlay">
<div class="popup">
<a class="close" href="#">×</a>
<div class="content">
<div class="social-fuctions">
Share to facebook
</div>
</div>
</div>
</div>
css code
h1 {
text-align: center;
font-family: Tahoma, Arial, sans-serif;
color: #06D85F;
margin: 80px 0;
}
.box {
width: 40%;
margin: 0 auto;
background: rgba(255,255,255,0.2);
padding: 35px;
border: 2px solid #fff;
border-radius: 20px/50px;
background-clip: padding-box;
text-align: center;
}
/*
.button {
font-size: 1em;
padding: 10px;
text-decoration: none;
cursor: pointer;
}
*/HTMLHTML
.social-fuctions{
display: flex;
}
.overlay {
position: fixed;
top: 0;
bottom: 0;
left: 0;
right: 0;
background: rgba(0, 0, 0, 0.2);
/* transition: opacity 100ms;*/
visibility: hidden;
opacity: 0;
}
.overlay:target {
visibility: visible;
opacity: 1;
}
.popup {
position: absolute;
bottom: -550px;
right: 5%;
left: 15%;
padding: 15px;
background: #fff;
border-radius: 5px;
width: 30%;
position: relative;
}
.popup .close {
position: absolute;
top: 20px;
right: 30px;
font-size: 30px;
font-weight: bold;
text-decoration: none;
color: #333;
}
.popup .close:hover {
color: #06D85F;
}
.popup .content {
max-height: 30%;
overflow: auto;
}
#media screen and (max-width: 700px){
.box{
width: 70%;
}
.popup{
width: 70%;
}
}
Any suggestion? Thanks a lot

Answer 1

Set your box to position: relative and make the modal box / pop up a child of the box div. This way, the overlay will be positioned absolutely within the parameters of it's parent div.
.box {
position: relative;
}
.modal {
position: absolute;
}
Something like this:
https://jsfiddle.net/bommy8zu/5/

Answer 2

Moosetuin's approach is simple and effective.
But there is no need for a relative parent. And a absolute Modal.
I made two examples one is just like Youtube's ShareBox and the other will allways be centered.
How To Center:
position: absolute;
transform: translate(-50%, -50%);
left: 50%;
top: 50%;
Check it out here: https://codepen.io/Tibixx/pen/zWEpqq