How to close Pop-Up in HTML?

This is a modal window made without JavaScript, nor jQuery, only with CSS.

.btn {
  position: relative;
  padding: 8px 16px;
  font-family: 'psychotik';
  font-size: 1.2em;
  font-weight: normal;
  color: #fff;
  text-shadow: none;
  border-radius: 16px;
  background: #00A6B6;
  box-shadow: inset 2px 2px 1px #007f8b;
}

.btn:hover {
  background: #FF9C00;
  box-shadow: inset 2px 2px 1px #995f02;
}

#modalContent {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 6;
  margin: -2% 0px 0px -150px;
  float: left;
  width: 300px;
  color: #fff;
  line-height: 22px;
  padding: 15px;
  border-radius: 5px;
  background: #00A6B6;
  border: 1px solid #fff;
  box-shadow: 0px 2px 1px #999;
}

#modal {
  position: fixed;
  top: 0px;
  left: 0px;
  z-index: 5;
  float: left;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.2);
  display: none;
  opacity: 0;
}

#modal>a {
  position: fixed;
  top: 0px;
  left: 0px;
  z-index: 1;
  float: left;
  width: 100%;
  height: 100%;
}

:target {
  display: block!important;
  opacity: 1!important;
}

#modalContent>a {
  position: absolute;
  top: -4px;
  right: -4px;
  color: #00A6B6;
  border-radius: 2px;
  background: #fff;
  padding: 4px;
}

<a href="#modal" title="" class="btn">Pincha aquí</a>
<!-- La modal -->
<div id="modal">
  <a href="#cerrar"></a>
  <div id="modalContent">
    <h1>Soy una ventana modal</h1>
    <p>Hecha sin JS ni jQuery, solo CSS3</p> <a href="#cerrar">X</a> </div>
</div>

Here's a pretty simple option:

Javascript Code

onclick=”window.opener.location.reload(); window.close();”

To the anchor href, leaving it alone # should reload the original page and therefore no longer show you the modal window

The truth, I will only replicate a "very similar" code that circulates on the web "among others". I will not go into details, because if you want more information the most fair is to visit the site that I take Reference:

Create modal window with CSS only

#popup {
  background-color: rgba(0,0,0,0.8);
  position: fixed;
  top:0;
  left:0;
  right:0;
  bottom:0;
  margin:0;
  -webkit-animation:autopopup 2s;
  -moz-animation:autopopup 2s;
  animation:autopopup 2s;
}

@-webkit-keyframes autopopup {
  from {opacity: 0;margin-top:-200px;}
  to {opacity: 1;}
}
@-moz-keyframes autopopup {
  from {opacity: 0;margin-top:-200px;}
  to {opacity: 1;}
}
@keyframes autopopup {
  from {opacity: 0;margin-top:-200px;}
  to {opacity: 1;}
}

#popup:target {
  -webkit-transition:all 1s;
  -moz-transition:all 1s;
  transition:all 1s;
  opacity: 0;
  visibility: hidden;
}

.popup-contenedor {
  position: relative;
  margin:7% auto;
  padding:30px 50px;
  background-color: #fafafa;
  color:#333;
  border-radius: 3px;
  width:50%;
}

a.popup-cerrar {
  position: absolute;
  top:3px;
  right:3px;
  background-color: #333;
  padding:7px 10px;
  font-size: 20px;
  text-decoration: none;
  line-height: 1;
  color:#fff;
}

<div class="modal-wrapper" id="popup">
  <div class="popup-contenedor">			
    <h2>Titulo de la Modal</h2>
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Dolor deleniti in porro, officia velit quaerat modi doloribus similique aspernatur impedit quod, laudantium reiciendis! Similique nihil eius esse, illum assumenda soluta!. </p>			
    <a class="popup-cerrar" href="#popup">X</a>			
  </div>
</div>