.box {
  width: 40%;
  margin: 0 auto;
  background: rgb(255,255,255,0.2);
  padding: 35px;
  border: 2px solid #fff;
  border-radius: 20px/50px;
  background-clip: padding-box;
  text-align: center;
}

.overlay {
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  background: rgb(0, 0, 0, 0.7);
  transition: opacity 300ms;
  visibility: hidden;
  opacity: 0;
}
.overlay:target {
  visibility: visible;
  opacity: 1;
}

.popup {
  margin: 70px auto;
  padding: 3px;
  background: #fff;
  border-radius: 9px;
  width: 25%;
  position: relative;
  transition: all 5s ease-in-out;
}

.popup .close {
  position: absolute;
  top: -10px;
  right: 1px;
  font-size: 40px;
  font-weight: bold;
  text-decoration: none;
  color: #fff;
  background:red;
}

.popup .content {
  max-height: 30%;
  overflow: auto;
  font-family:arial;
}

@media screen and (max-width: 700px){
  .box{
    width: 70%;
  }
  .popup{
    width: 70%;
  }
}