A Pen by Benjamin Dalton.

index.html

<div id="overlay" class="cover blur-in">
  <div class="content">
    <h1>The history or Lorem Ipsum</h1>
    <span>
    Contrary to popular belief, Lorem Ipsum is not simply random text. It has roots in a piece of classical Latin literature from 45 BC, making it over 2000 years old. Richard McClintock, a Latin professor at Hampden-Sydney College in Virginia, looked up one of the more obscure Latin words, consectetur, from a Lorem Ipsum passage, and going through the cites of the word in classical literature, discovered the undoubtable source. Lorem Ipsum comes from sections 1.10.32 and 1.10.33 of "de Finibus Bonorum et Malorum" (The Extremes of Good and Evil) by Cicero, written in 45 BC. This book is a treatise on the theory of ethics, very popular during the Renaissance. The first line of Lorem Ipsum, "Lorem ipsum dolor sit amet..", comes from a line in section 1.10.32.
    </span>
    <span>
      <p>
        Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse faucibus viverra porta. Pellentesque scelerisque eros quis dignissim semper. Nulla ut justo a sapien lobortis posuere. Maecenas scelerisque justo eleifend risus dapibus, id bibendum tellus placerat. Sed massa diam, ornare ut varius ut, auctor non arcu. Cras rutrum tortor eu diam feugiat aliquam. Suspendisse rutrum pretium pretium. 
      </p>
    </span>
    <span>
    It is a long established fact that a reader will be distracted by the readable content of a page when looking at its layout. The point of using Lorem Ipsum is that it has a more-or-less normal distribution of letters, as opposed to using 'Content here, content here', making it look like readable English. Many desktop publishing packages and web page editors now use Lorem Ipsum as their default model text, and a search for 'lorem ipsum' will uncover many web sites still in their infancy. Various versions have evolved over the years, sometimes by accident, sometimes on purpose (injected humour and the like).
    </span>
  </div>
</div>
<div class="row pop-up">
  <div class="box small-6 large-centered">
    <a href="#" class="close-button">&#10006;</a>
    <h3>lorem ipsum</h3>
    <p>Integer non odio id ante rutrum dictum. Nam ac dapibus felis, at pharetra sapien. </p>
    <p>Maecenas lacus nisi, pellentesque a congue vel, rhoncus sit amet lacus. Sed mattis ultrices risus in tincidunt. Fusce congue enim iaculis, lacinia mi ut, euismod ligula. Donec nec volutpat tortor, vel iaculis lacus. Nullam congue lorem nec maximus congue. Aliquam erat volutpat. </p>
    <a href="#" class="button">Learn More</a>
  </div>
</div>

Pop-up-with-blurred-background-animation.markdown

Pop-up with blurred background animation

Here's a popup that appears while blurring out the body underneath. click the 'X' close on the popup and the blur transition back while the popup fades off.

Suitable for sites that may want a nag (perhaps for donation or subscription services) or could be re-purposed as a general modal or lightbox.

Uses CSS3 Filter (for blur) and CSS3 Animation for blur transitions. The jQuery is minimal in this iteration, simply used to fade in the pop-up and add and remove the CSS3 classes for blurring.

A Pen by Benjamin Dalton on CodePen.

License.

script.js

$(function() {
  $('.pop-up').hide();
  $('.pop-up').fadeIn(1000);
  
      $('.close-button').click(function (e) { 

      $('.pop-up').fadeOut(700);
      $('#overlay').removeClass('blur-in');
      $('#overlay').addClass('blur-out');
      e.stopPropagation();
        
    });
 });

style.css

body {
    background-color: #FCFCFC;
}

.cover {
    height: 100%;
    width: 100%;
    position: absolute;
    z-index: 1;
}

.blur-in {
    -webkit-animation: blur 2s forwards;
    -moz-animation: blur 2s forwards;
    -o-animation: blur 2s forwards;
    animation: blur 2s forwards;
}

.blur-out {
    -webkit-animation: blur-out 2s forwards;
    -moz-animation: blur-out 2s forwards;
    -o-animation: blur-out 2s forwards;
    animation: blur-out 2s forwards;
}

@-webkit-keyframes blur {
    0% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }

    100% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }
}

@-moz-keyframes blur {
    0% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }

    100% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }
}

@-o-keyframes blur {
    0% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }

    100% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }
}

@keyframes blur {
    0% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }

    100% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }
}

@-webkit-keyframes blur-out {
    0% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }

    100% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }
}

@-moz-keyframes blur-out {
    0% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }

    100% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }
}

@-o-keyframes blur-out {
    0% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }

    100% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }
}

@keyframes blur-out {
    0% {
        -webkit-filter: blur(4px);
        -moz-filter: blur(4px);
        -o-filter: blur(4px);
        -ms-filter: blur(4px);
        filter: blur(4px);
    }

    100% {
        -webkit-filter: blur(0px);
        -moz-filter: blur(0px);
        -o-filter: blur(0px);
        -ms-filter: blur(0px);
        filter: blur(0px);
    }
}

.content {
    width: 650px;
    margin: 0 auto;
    padding-top: 100px;
}

span {
    color: dimgray;
}

.pop-up {
    position: fixed;
    margin: 5% auto;
    left: 0;
    right: 0;
    z-index: 2;
}

.box {
    background-color: whitesmoke;
    text-align: center;
    margin-left: auto;
    margin-right: auto;
    margin-top: 10%;
    position: relative;
    -webkit-box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
    -moz-box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
    box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
}

.button {
    margin 0 auto;
  background-color: #FF8566;
    margin-bottom: 33px;
}

.button:hover {
    background-color: #7CCF29;
    -webkit-box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
    -moz-box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
    box-shadow: 0px 4px 6px 0px rgba(0,0,0,0.1);
}

.close-button {
    transition: all 0.5s ease;
    position: absolute;
    background-color: #FF9980;
    padding: 1.5px 7px;
    left: 0;
    margin-left: -10px;
    margin-top: -9px;
    border-radius: 50%;
    border: 2px solid #fff;
    color: white;
    -webkit-box-shadow: -4px -2px 6px 0px rgba(0,0,0,0.1);
    -moz-box-shadow: -4px -2px 6px 0px rgba(0,0,0,0.1);
    box-shadow: -3px 1px 6px 0px rgba(0,0,0,0.1);
}

.close-button:hover {
    background-color: tomato;
    color: #fff;
}

h3 {
    text-align: center;
    padding-top: 15px;
    padding-bottom: 15px;
    color: #fff;
    background-color: #FF704D;
}

p {
    padding: 20px 65px 10px 65px;
    color: dimgray;
}

h1 {
    color: dimgray;
    font-family: Garamond, Baskerville, "Baskerville Old Face", "Hoefler Text", "Times New Roman", serif;
}