body{
  margin: 0;
  padding: 0;
  font-family: "montserrat";
}
section{
  width: 100%;
  height: 100vh;
  background: url(bg.jpg) no-repeat;
  background-size: cover;
}
#topBtn{
  position: fixed;
  bottom: 40px;
  right: 40px;
  font-size: 40px;
  width: 50px;
  height: 50px;
  border: none;
  cursor: pointer;
  display: none;
}
@media (max-width: 375px) {
  #topBtn{
    bottom: 5px;
    right: 5px;
    font-size: 20px;
    width: 30px;
    height: 30px;
  }
}
@media (min-width: 375px)and (max-width:425px) {
  #topBtn{
    bottom: 5px;
    right: 5px;
    font-size: 25px;
    width: 30px;
    height: 30px;
  }
}
@media (min-width: 426px)and (max-width:768px) {
  #topBtn{
    bottom: 5px;
    right: 5px;
    font-size: 30px;
    width: 35px;
    height: 35px;
  }
}
@media (min-width: 769px)and (max-width:1024px) {
  #topBtn{
    bottom: 5px;
    right: 5px;
    font-size: 30px;
    width: 35px;
    height: 35px;
  }
}
@media (min-width: 1025px)and (max-width:1440px) {
  #topBtn{
    bottom: 5px;
    right: 5px;
    font-size: 30px;
    width: 40px;
    height: 40px;
  }
}