body {
  background-color: white;
  width: 100%;
  margin: 0;
  padding: 0;
}

header {
  width: 95%;
  margin: 20px auto 0;
  display: flex;
  flex-flow: column;
}

hr {
  margin: 0;
}

#time {
  align-self: end;
}

nav {
  display: flex;
  justify-content: space-between;
  border: 2px solid black;
  padding: 5px 10px;
}

nav h3 {
  margin: 0;
}

nav a {
  text-decoration: none;
  color: black;
}

nav a:hover {
  color: blue;
}

nav ul {
  display: flex;
  justify-content: space-between;
  list-style-type: none;
  gap: 20px;
  margin: 0;
}

nav li {
  display: flex;
  gap: 15px;
}

button {
  border: 3px solid black;
  cursor: pointer;
  background-color: #fff;
  font-weight: bolder;
}

#booksSection {
  border: 2px solid black;
  width: 95%;
  margin: 0 auto;
}

#booksSection h3 {
  text-align: center;
}

#booksSection ul {
  margin: 0;
  padding: 0;
}

form button {
  width: 60px;
  align-self: end;
}

#booksSection li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 5px 8px;
  margin: 0;
}

#booksSection li:nth-child(odd) {
  background-color: rgb(247, 241, 241);
}

.form-section {
  display: flex;
  flex-flow: column;
  justify-content: center;
  align-items: center;
}

form {
  display: flex;
  flex-flow: column;
  gap: 10px;
  width: 60%;
  margin: 0 auto;
}

form label {
  display: flex;
  width: 100%;
}

form input {
  padding: 3px 3px;
  width: 100%;
}

#contact {
  display: none;
  flex-flow: column;
  width: 60%;
  margin: 0 auto;
}

#contact h3 {
  text-align: center;
}

#contact p {
  margin: 0;
}

footer {
  width: 95%;
  display: flex;
  margin: 40px auto 0;
}

footer > * {
  border: 2px solid black;
  width: 100%;
  margin: 0;
  padding: 5px 5px;
}

.active_menu {
  color: blue;
}

.disappear {
  display: none;
}

.visible {
  display: block;
}