.main-nav{
    margin-top: 10px;
    list-style: none;
    padding-left: 0;
    background-color: #13a4a4;
}
.main-nav-item{
    display: inline-block;
    border-right: 1px solid #ffffff;
}
.main-nav-item a{
    color: white;
    padding: 2px 8px;
    text-decoration: none;
    border-radius: 2px;
    /*background-color: #ff0000;*/
}
.main-nav-item a:hover{
    color: #0000ff;
}
.main-nav-item a:active{
    color: chocolate;
}
/*
.main-nav-item a::after{
    content: " | ";
}*/
main{
    width: 100%;
    height: 500px;
    border: 10px solid gray;
    padding: 20px 35px;
}
.btn-volver {
  position: fixed;
  top: 15px;
  right: 15px;
  background-color: #1a2b4c;
  color: #ffffff;
  padding: 10px 18px;
  text-decoration: none;
  border-radius: 20px;
  font-size: 0.9rem;
  font-weight: bold;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.25);
  z-index: 9999;
  transition: all 0.3s ease;
}

.btn-volver:hover {
  background-color: #2563eb;
  transform: scale(1.05);
}