.topnav {
  background-color: #2A8C7F;
  overflow: hidden;
  position: sticky;
  top: 0;
  width: 100%;
  z-index: 1000;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.topnav a {
  float: left;
  color: white;
  text-align: center;
  padding: 14px 20px;
  text-decoration: none;
  font-size: 17px;
  transition: background-color 0.3s ease;
}

.topnav a:hover {
  background-color: #28675E;
  background-color: rgb(83, 166, 152);
  color: white;
}

.topnav a.active {
  background-color: #28675E;
  color: white;
  text-shadow: 0 0 1px currentColor;
  cursor: default;
}

.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 a.icon {
    position: absolute;
    right: 0;
    top: 0;
  }
  .topnav.responsive a {
    float: none;
    display: block;
    text-align: left;
  }
}