.blocker {
  position: fixed;
  top: 0; right: 0; bottom: 0; left: 0;
  width: 100%; height: 100%;
  overflow: auto;
  z-index: 999999998;
  padding: 20px;
  box-sizing: border-box;
  background-color: rgb(0,0,0);
  background-color: rgba(0,0,0,0.75);
  text-align: center;
}
.blocker:before{
  content: "";
  display: inline-block;
  height: 100%;
  vertical-align: middle;
  margin-right: -0.05em;
}
.blocker.behind {
  background-color: transparent;
}
.modal {
  display: inline-block;
  vertical-align: middle;
  position: relative;
  z-index: 2;
  max-width: 75%;
  box-sizing: border-box;
  width: 90%;
  background: #fff;
  padding: 100px;
  -webkit-box-shadow: 0 0 10px #000;
  -moz-box-shadow: 0 0 10px #000;
  -o-box-shadow: 0 0 10px #000;
  -ms-box-shadow: 0 0 10px #000;
  box-shadow: 0 0 10px #000;
  text-align: left;
}

.modal a.close-modal {
  position: absolute;
  top: 10px;
  right: 10px;
  display: block;
}