.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.3rem 2rem;
}

#logo {
  text-decoration: none;
  color: #000;
  font-size: 16px;
  cursor: pointer;
  white-space: nowrap;
}

.hamburger {
  display: none;
}

#nav-links {
  display: flex;
  list-style-type: none;
  font-size: 1rem;
  gap: 3rem;
  padding-top: 1rem;
}

#nav-links li {
  cursor: pointer;
}

.add-new-book {
  display: none;
}

.add-contact-info {
  display: none;
}

.books-list {
  display: none;
}

.display-section {
  display: block;
}

.hidden {
  display: none;
}

.contact-info {
  margin: 6rem 2rem;
  font-size: 1.5rem;
}

.contact-info ul {
  list-style: none;
}

footer p {
  margin-top: 90vh;
  margin-left: 1rem;
}

.task {
  display: flex;
  justify-content: space-around;
}

@media screen and (max-width: 520px) {
  header {
    padding: 5px 20px;
    z-index: 3;
    background-color: white;
  }

  nav {
    width: 100vw;
    position: absolute;
    top: 48px;
    left: 0;
    transform: translateX(-500px);
    background-color: white;
    display: flex;
    justify-content: center;
    transition: transform 0.3s ease-in-out;
  }

  #nav-links {
    padding-left: 0;
  }

  nav.active {
    transform: translateX(0);
    z-index: 1;
  }

  .hamburger {
    display: block;
    cursor: pointer;
    width: fit-content;
  }

  .bar {
    display: block;
    width: 28px;
    height: 4px;
    margin: 5px auto;
    -webkit-transition: all 0.3s ease-in-out;
    transition: all 0.3s ease-in-out;
    background-color: #000;
  }

  .hamburger.active .bar:nth-child(2) {
    opacity: 0;
  }

  .hamburger.active .bar:nth-child(1) {
    transform: translateY(9px) rotate(45deg);
  }

  .hamburger.active .bar:nth-child(3) {
    transform: translateY(-9px) rotate(-45deg);
  }

  .contact-info {
    font-size: 15px;
  }

  .contact-info p {
    text-align: center;
    padding: 0 15px;
  }
}