index.css

/* CSS style */
*::before,
*::after {
  padding: 0;
  margin: 0;
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}

body {
  min-height: 100vh;
  display: flex;
  max-width: 1440px;
  flex-direction: column;
  justify-content: space-between;
  font-family: Arial, Helvetica, sans-serif;
}

a {
  text-decoration: none;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  max-width: 1100px;
  margin: 10px auto 0 auto;
  padding: 10px 15px;
}

.logo a {
  color: #000;
  font-size: x-large;
  font-weight: bold;
}

.nav-list {
  list-style: none;
  display: flex;
  align-items: center;
}

.nav-list > *:not(:last-child) {
  border-right: 2px solid #000;
}

.nav-item {
  padding: 15px 10px;
}

.nav-link {
  color: #000;
  cursor: pointer;
  padding: 15px 10px;
  border: 1px solid #fff;
}

.nav-link:hover {
  color: blue;
}

.header {
  width: 100%;
  max-width: 1440px;
  margin: 5px auto;
}

.date {
  text-align: right;
  margin: 10px auto;
  padding: 20px;
  padding-right: 150px;
}

.main {
  display: flex;
  flex-direction: column;
}

.all-books {
  width: 100%;
  max-width: 1440px;
  margin: 0 auto;
  min-height: 440px;
}

.hide {
  display: none !important;
}

.added-bklist {
  width: 100%;
  border: 3px solid black;
}

.added-bklist div {
  border: 1px solid lightgray;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px;
}

.added-bklist div:nth-child(odd) {
  background-color: lightgray;
}

.add-book {
  max-width: 700px;
  margin: 0 auto;
  min-height: 300px;
  margin-bottom: 130px;
}

.title,
.author {
  text-transform: capitalize;
}

.form {
  display: flex;
  flex-direction: column;
}

.input-container {
  max-width: 500px;
  width: auto;
}

input {
  padding: 15px;
  width: 100%;
  border: 1px solid black;
}

input::-webkit-input-placeholder {
  color: black;
}

.form button {
  align-self: flex-end;
  padding: 8px 20px;
  font-size: 17px;
  border: 2px solid green;
  background-color: purple;
  color: #fff;
  box-shadow: 5px 7px 5px rgb(65, 221, 73);
  transition: box-shadow 0.2s;
}

.remove {
  align-self: flex-end;
  padding: 8px 20px;
  font-size: 17px;
  border: 2px solid red;
  background-color: red;
  color: #fff;
  box-shadow: 5px 7px 5px rgb(240, 57, 57);
  transition: box-shadow 0.2s;
}

.form button:active,
.remove:active {
  box-shadow: 2px 2px 2px rgba(0, 0, 0, 0.8);
}

.contact {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 200px;
  max-width: 500px;
  margin: 0 auto;
}

h2 {
  text-align: center;
  font-size: xx-large;
  margin-bottom: 30px;
}

.contact-list {
  margin-left: 30px;
}

.footer {
  border: 3px solid rgb(43, 43, 43);
  background-color: rgb(43, 43, 43);
  color: #fff;
  margin: 0 auto 15px auto;
  width: 100%;
  max-width: 1440px;
  padding: 15px;
  justify-self: flex-end;
}