sergio9508/popup.css

## popup.css
.overlay {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(0, 0, 0, 0.7);
  transition: opacity 500ms;
  visibility: hidden;
  opacity: 0;
}
.overlay:target {
  visibility: visible;
  opacity: 1;
  z-index: 99;
}
#popupBody {
  width: 50%;
  padding: 1%;
  border-radius: 15px;
  position: relative;
  transition: all 5s ease-in-out;
  z-index: 0;
  margin: 2% auto;
}
.popupContent{
  display: flex;
  justify-content: center;
  align-items: center;
}
iframe{
  border-color: black;
}
#cerrar {
  position: absolute;
  top: 20px;
  left: 10px;
  transition: all 200ms;
  font-size: 30px;
  font-weight: bold;
  text-decoration: none;
  color: white;
}
.imagen{
  max-width: 100%;
}
.container{
  max-width: 1100px;
  display: block;
  margin: auto;
}

## popup.html
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <link rel="stylesheet" href="./style.css">
  <title>Document</title>
</head>

<body>
  <div class="container">
    <a href="#popup"><img class="imagen" src="./ciencia-del-universo-1530540262286.jpg" alt="" srcset=""></a>

    <p class="video-description">hello</p>
    <div id="popup" class="overlay">
      <div id="popupBody">
        <h2>Terms and conditions</h2>
        <a id="cerrar" href="#">&times;</a>
        <div class="popupContent">
          <iframe class="video"
        src="https://www.youtube.com/embed/_SKbW8gnLFM" width="640" height="480">
        </div>
      </div>
    </div>
  </div>
</body>

</html>