style.css

main {
  margin: auto;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  height: 100vh;
}

h2,
h1 {
  text-align: center;
}

nav {
  border: 3px solid #000;
  display: flex;
  justify-content: space-between;
  width: 95vw;
  height: auto;
  margin: 0;
  padding: 5px;
}

#top-nav {
  display: flex;
  align-items: center;
  padding-right: 10px;
  height: auto;
  margin: 0;
}

#con-link1 a,
#con-link2 a {
  border-right: 2px solid;
}

#top-nav li a {
  color: #000;
  font-size: 20px;
  font-weight: lighter;
  padding: 5px;
  text-decoration: none;
}

#top-nav li.active a {
  color: blue;
  border-color: #000;
}

ul {
  list-style: none;
}

#top-header {
  font-weight: lighter;
  display: flex;
  align-items: center;
  margin: 0;
}

#add {
  width: 50%;
  height: 70vh;
}

.contacts h2 {
  font-size: xx-large;
}

#add h2 {
  font-size: xx-large;
}

.all-book li {
  display: flex;
  justify-content: space-between;
  list-style: none;
  margin: 0;
  width: auto;
  padding: 10px;
  gap: 10px;
}

.all-book li .title {
  font-weight: 600;
}

#all-book {
  width: 96vw;
  height: 70vh;
}

#all-book h2 {
  font-size: xx-large;
}

.all-book {
  padding: 0;
  border: 3px solid #000;
}

.all-book li:nth-child(odd) {
  background-color: rgb(222, 222, 222);
}

#formAdd {
  height: auto;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: flex-start;
  gap: 2px;
  padding: 50px;
}

#formAdd input {
  margin: 0;
  border: 3px solid;
  width: 100%;
  padding: 10px;
}

button {
  border-radius: 0;
}

hr {
  border-bottom: 2px solid #000;
  width: 10%;
}

footer p {
  color: #000;
  font-size: 20px;
  font-weight: lighter;
  padding: 9px;
  border: 3px solid;
  width: 95vw;
}

#date {
  width: 96vw;
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.Rbtn {
  background-color: #fff;
  border: 3px solid;
  padding: 3px 12px;
  box-shadow: 2px 2px 1px;
}

.btn {
  border: 3px solid;
  margin-top: 30px;
  padding: 3px 12px;
  box-shadow: 2px 2px 1px;
}

#contacts-ul {
  list-style-type: disc;
  margin-left: 30px;
}

.contacts {
  height: 70vh;
  width: 96vw;
  display: flex;
  align-items: center;
  flex-direction: column;
}

.show {
  display: none;
}