#installPopup {
  display:none;
  position:fixed;
  top:50%;
  left:50%;
  transform:translate(-50%,-50%);
  background:#fff;
  padding:20px;
  border-radius:12px;
  box-shadow:0 4px 15px rgba(0,0,0,0.2);
  z-index:9999;
  text-align:center;
  width:300px;
}
#installPopup h3 {
  margin:0 0 10px;
  font-size:18px;
}
#installPopup p {
  margin:0 0 15px;
  font-size:14px;
  color:#555;
}
#installPopup button {
  background:#0073e6;
  color:#fff;
  border:none;
  padding:10px 20px;
  border-radius:8px;
  cursor:pointer;
}
#installPopup #closePopup {
  position:absolute;
  top:10px;
  right:15px;
  cursor:pointer;
  font-size:18px;
}