index.css

/* Meta description */

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

/* general */

body {
  flex-direction: column;
  font-family: 'Outfit', sans-serif;
}

.contact-us h1,
.add-books h1,
#books h1 {
  text-align: center;
  font-size: 40px;
  font-weight: 700;
  margin-bottom: 3%;
}

section {
  display: none;
}

section:target {
  display: block;
}

.content {
  display: flex;
  justify-content: center;
  align-items: center;
}

.content > * {
  width: 100%;
}

/* header */

header {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  justify-content: space-between;
  padding: 20px;
  border: 2px solid #000;
  margin: 5px 10px;
  background-color: #fff;
}

.sticky {
  position: fixed;
  top: 0;
}

.nav-link-list {
  display: flex;
  list-style-type: none;
}

.nav-item {
  padding: 10px 25px;
  border-right: 2px solid #000;
}

.nav-item:last-child {
  border-right: none;
}

.nav-link:link,
.nav-link:visited {
  text-decoration: none;
  color: #000;
}

.nav-link:hover,
.nav-link:active {
  color: rgb(93, 93, 169);
}

/** stylelint quick fixes */

#contact-us > p {
  text-align: center;
  font-size: 22px;
}

/* book section */

#books {
  padding-top: 5%;
  margin-bottom: 2%;
}

#book-list {
  list-style: none;
  border: 2px solid black;
  width: 98%;
  min-height: 50px;
  height: max-content;
  margin: auto;
}

#book-list li {
  padding: 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

#book-list li:nth-child(odd) {
  background-color: #dbd7d7;
}

#book-list > li > p {
  padding-bottom: 5px;
}

.remove-btn {
  border: 2px solid black;
  padding: 5px 5px;
  display: block;
  cursor: pointer;
}

/* add book section */

#add-books {
  margin-left: 25%;
  margin-right: 20%;
}

form {
  text-align: right;
  width: 80%;
}

form div {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  width: 100%;
}

input {
  padding: 10px;
  width: 100%;
  height: 45px;
  border: 2px solid black;
}

#addBtn {
  margin-top: 15px;
  background-color: #fff;
  border: 2px solid black;
  padding: 5px;
  cursor: pointer;
}

/* contact us section */

.contact-list {
  display: flex;
  flex-direction: column;
  gap: 15px;
  margin-left: 30%;
  margin-right: 20%;
  width: 60%;
  margin-top: 3%;
  font-size: 22px;
}

/* footer section */

.footer {
  height: 10%;
  width: 96%;
  padding: 15px;
  border: 2px solid black;
  margin: 2%;
  position: fixed;
  bottom: 0;
  background-color: #fff;
}

#now {
  margin-left: 75%;
}