.button {
  font-family: Tahoma, Arial, sans-serif;
  font-size: 0.7em;
  font-weight:bold;
  color: #ff0;
  text-decoration: none;
}
.overlay {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgba(0, 0, 0, 0.7);
  transition: opacity 500ms;
  visibility: hidden;
  z-index:998;
  opacity: 0;
}
.overlay:target {
  visibility: visible;
  opacity: 1;
}
.popup {
  margin: 70px auto;
  padding: 20px;
  background: #fff;
  border-radius: 5px;
  width: 40%;
  position: relative;
  z-index:1000;
}
.popup h2 {
  margin-top: 0;
  color:#33F;
  font-family: Tahoma, Arial, sans-serif;
}
.popup .close {
  position: absolute;
  top: 10px;
  right: 30px;
  transition: all 200ms;
  font-size: 30px;
  font-weight: bolder;
  text-decoration: none;
  background: #fff;
  color: #900;
}
.popup .close:hover {
  color: #f88;
}
.popup .content {
  font-family: Tahoma, Arial, sans-serif;
  color:#36F;
  max-height: 30%;
  overflow: auto;
}
@media screen and (max-width: 700px){
  .box{
    width: 70%;
  }
  .popup{
    width: 70%;
  }
}