.topnav {
  overflow: hidden;
  background-color: #333;
}

.topnav a {
  float: left;
  display: block;
   font-weight: bold;
  color: #f2f2f2;
  text-align: center;
  padding: 10px 10px;
  text-decoration: none;
  font-size: 18px;
}

.topnav a:hover {
  background-color: #e60000;
  color: black;
}

.topnav a.active {
  background-color: #e60000;
  color: white;
}

.topnav .icon {
  display: none;
}

@media screen and (max-width: 600px) {
  .topnav a:not(:first-child) {display: none;}
  .topnav a.icon {
    float: right;
    display: block;
  }
}

@media screen and (max-width: 600px) {
  .topnav.responsive {position: relative;}
  .topnav.responsive .icon {
    position: absolute;
    right: 0;
    top: 0;
  }
  .topnav.responsive a {
    float: none;
    display: block;
    text-align: left;
  }
}





#myBtn {
  display: inline-block;
  background-color: #ff0000 ;
  width: 50px;
  height: 50px;
  text-align: center;
  border-radius: 4px;
  position: fixed;
  bottom: 30px;
  right: 30px;
  transition: background-color .3s, 
    opacity .5s, visibility .5s;
  opacity: 0;
  visibility: hidden;
  z-index: 1000;
}
#myBtn::after {
  content: "\f077";
  font-family: FontAwesome;
  font-weight: normal;
  font-style: normal;
  font-size: 2em;
  line-height: 50px;
  color: #fff;
}
#myBtn:hover {
  cursor: pointer;
  background-color: #ff0000 ;
}
#myBtn:active {
  background-color: #ff0000 ;
}
#myBtn.show {
  opacity: 1;
  visibility: visible;
}


@media (max-width: 500px) {

  #myBtn {
  bottom: 10px;
  right: 10px;
  }