.popup {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.6);
  z-index: 9999;
}

.popup-content {
  width: 90%;
  max-width: 500px;
  padding: 30px;
  background: #fff;
  border-radius: 8px;
  margin: 100px auto;
  position: relative;
}

.close {
  position: absolute;
  top: 10px;
  right: 15px;
  border: none;
  background: none;
  font-size: 24px;
  cursor: pointer;
}