<div class="support-backdrop-filter"></div>

<div class="container">
  <div id="first-element" class="filter">
    <a href="https://goo.gl/MtKrik" class="button">Button</a>
  </div>
  <a href="https://goo.gl/MtKrik">
    <img id="second-element" src="https://s3-us-west-2.amazonaws.com/s.cdpn.io/210284/red-riding-hood.jpg" alt="">
  </a>
</div>
body {
  background-color: #333;
}
a {
   display: block;
}
img {
  width: 100%;
  max-width: 700px;
  height: 100%;
  display: block;
}
.container {
    margin-top: 40px;
    max-width: 700px;
    width: 100%;
    margin-right: auto;
    margin-left: auto;
    position: relative;
}
.filter {
    position: absolute;
    top: 0;
    left: 0;
    transform: translate3d( 40%, 30%, 0 );
    width: 60%;
    height: 60%;
    z-index: 30;
    -webkit-backdrop-filter: blur(10px);
    backdrop-filter: blur(10px);
    background-color: rgba(255, 255, 255, 0.2);
}

/**
 * Extras 
 **/

.filter {
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
}
.button {
  padding: 20px 26px;
  background-color: #ec3b12;
  display: block;
  border-radius: 3px;
  text-transform: uppercase;
  color: #fff;
  text-decoration: none;
  font-weight: 600;
}

.button:hover {
  background-color: #ac1711;
}

External CSS

  1. https://codepen.io/tutsplus/pen/ZpvWBO/

External JavaScript

This Pen doesn't use any external JavaScript resources.