body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  text-align: center;
  background: #f5f5f5;
}

header {
  padding: 20px;
}

nav a {
  margin: 0 10px;
  text-decoration: none;
  color: black;
  font-weight: bold;
}

main {
  background: white;
  margin: 40px auto;
  padding: 20px;
  width: 90%;
  max-width: 600px;
  border-radius: 8px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

p {
  text-align: left;
}

.books-table {
  width: auto;             /* let the table width fit content */
  border-collapse: collapse;
  margin: 20px auto;       /* center the table horizontally and add top/bottom margin */
}

.books-table th,
.books-table td {
  border: 1px solid #333;
  padding: 10px 20px;      /* more space top/bottom 10px, left/right 20px */
  text-align: left;
}

.books-table th {
  background-color: white;
  font-weight: bold;
}