* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

header {
  display: flex;
  justify-content: space-around;
  width: 80%;
  margin: auto;
  background-color: black;
}

.logo_imagen {
  width: 15%;
  margin: 2%;
}

.logo_imagen img {
  width: 100%;
  object-fit: cover;
  object-position: top;
  border-radius: 50%;
}

.logo_texto {
  width: 85%;
}

nav {
  display: flex;
  width: 80%;
  justify-content: space-evenly;
  margin: 2vh auto;
  background-color: blue;
}

nav a {
  font-size: x-large;
  color: white;
  text-decoration: none;
  margin: 2px;
  padding: 5px;
  border-radius: 25%;
  width: 10%;
}

nav a:hover {
  color: red;
  background-color: blue;
}

.contenedor {
  display: flex;
  width: 80%;
  margin: auto;
  justify-content: space-around;
  flex-wrap: wrap;
}

.contenedor .libro {
  width: 20%;
  display: flex;
  justify-content: center;
  align-items: center;
  margin: 15px auto;
}

.contenedor .libro img {
  width: 80%;
}

.contenedor .libro img:hover {
  cursor: pointer;
}

.contenedor .overlay {
  display: flex;
  align-items: center;
  position: fixed;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
  visibility: hidden;
  background-color: rgb(0, 0, 0);
}

.contenedor .overlay .cierre {
  color: white;
  background-color: teal;
  width: 7%;
  text-align: center;
}

.contenedor .overlay .cierre:hover {
  cursor: pointer;
}

.contenedor .overlay .next {
  color: white;
  background-color: teal;
  width: 7%;
  text-align: center;
  visibility: hidden;
}

.contenedor .overlay .next:hover {
  cursor: pointer;
}

.contenedor .overlay .visor {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 86%;
  margin: auto;
}

.contenedor .overlay .visor .titulo {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.contenedor .overlay .visor .titulo .pdf {
  display: block;
  width: 100%;
}

.contenedor .overlay .visor .titulo .pdf a {
  color: white;
  text-decoration: none;
}

.contenedor .overlay .visor .titulo .caras {
  display: flex;
  justify-content: space-around;
}

.contenedor .overlay .visor .titulo .caras img {
  width: 100%;
  margin: 10% auto;
}

/****************************************/

@media screen and (min-width: 481px) and (max-width: 768px) {
  .contenedor .libro {
    width: 30%;
  }

  .overlay {
    flex-direction: column;
    justify-content: space-evenly;
  }

  .contenedor .overlay .cierre {
    width: 50%;
    margin: 5% 0 0 0;
  }

  .contenedor .overlay .next {
    width: 50%;
    visibility: hidden;
    position: fixed;
    bottom: 10%;
  }
}

/****************************************/

@media screen and (max-width: 480px) {
  .contenedor .libro {
    width: 50%;
  }

  .overlay {
    flex-direction: column;
    justify-content: center;
  }

  .contenedor .overlay .cierre {
    width: 50%;
    margin: 5% 0 0 0;
  }

  .contenedor .overlay .next {
    width: 50%;
    visibility: hidden;
    position: fixed;
    bottom: 5%;
  }

  .caras img {
    margin: 0;
    width: 65%;
  }
}