Модальное окно css

HTML

<a href="#openModal">Open Modal</a>
<div id="openModal" class="modalDialog">
  <div>
    <a class="close" title="Close" href="#close">X</a>
    <h2>Modal Box</h2>
    <p>This is a sample modal box that can be created using the powers of CSS3.</p>
    <p>You could do a lot of things here like have a pop-up ad that shows when your webs
      ite loads, or creata     login/register form for users.
    </p>
  </div>
</div>

<a href = "#openAsdf">asdf</a>

<a id = "openAsdf" href = "#close">d
  
</a>
<div class = "modalAsdf">
    asdf
  </div>

CSS

.modalDialog {
    background: none repeat scroll 0 0 rgba(0, 0, 0, 0.8);
    bottom: 0;
    font-family: Arial,Helvetica,sans-serif;
    left: 0;
    opacity: 0;
    pointer-events: none;
    position: fixed;
    right: 0;
    top: 0;
    transition: opacity 400ms ease-in 0s;
    z-index: 99999;
}
.modalDialog:target {
    opacity: 1;
    pointer-events: auto;
}
.modalDialog > div {
    background: linear-gradient(#fff, #999) repeat scroll 0 0 rgba(0, 0, 0, 0);
    border-radius: 10px;
    margin: 10% auto;
    padding: 5px 20px 13px;
    position: relative;
    width: 400px;
}
.close {
    background: none repeat scroll 0 0 #606061;
    border-radius: 12px;
    box-shadow: 1px 1px 3px #000;
    color: #ffffff;
    font-weight: bold;
    line-height: 25px;
    position: absolute;
    right: -12px;
    text-align: center;
    text-decoration: none;
    top: -10px;
    width: 24px;
}
.close:hover {
    background: none repeat scroll 0 0 #00d9ff;
}

#openAsdf {
  border: 1px solid green;
  display: block;
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0, 0, 0, .5)
}