* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    border: 0;
    font-size: 18px;
    font-family: "Ubuntu Mono", monospace;
  }
  
  html, body {
    height: 100%;
  }
  
  body {
    line-height: 1.5;
    background-color: #F1F3F6;
    color: #34495E;
  }
  
  header {
    text-align: center;
    padding-top: 20px;
  }
  
  header a {
    font-size: 36px;
    font-weight: bold;
    height: 36px;
    text-decoration: none;
    list-style: none;
  }
  
  header a {
    color: #34495E;
    text-decoration: none;
  }
  
  h1 a:hover {
    text-decoration: none;
    color: #34495E;
  }
  
  header a:visited {
    color: initial;
    text-decoration: none;
  }
  
  nav ul {
    display: flex;
    flex-flow: row nowrap;
    justify-content: right;
    list-style: none;
    background: #ffffff;
  }
  
  nav a {
    display: block;
    text-decoration: none;
    color: #6A6C6F;
    text-align: center;
    padding: 10px;
    padding-right: 25px;
  }
  
  nav a:hover {
    background: whitesmoke;
    color: black;
  }
  
  main {
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
  }
  
  table {
    background: white;
    border: 1px solid #E4E5E7;
    border-collapse: collapse;
    width: 100%;
  }
  
  td, th {
    text-align: left;
    padding: 9px 18px;
  }
  
  th:last-child, td:last-child {
    text-align: right;
    color: #6A6C6F;
  }
  
  tr {
    border-bottom: 1px solid #E4E5E7;
  }
  
  tr:nth-child(2n) {
    background-color: #F7F9FA;
  }
  
  td a {
    color: #1577da;
    text-decoration: none;
  }
  
  /* class selector for book-details */
  .book-details ul {
    list-style-type: none;
  }
  
  footer {
    border-top: solid 1px;
    background: #F7F9FA;
    width: 100%;
    height: 40px;
    padding-top: 10px;
    position: absolute;
    bottom: 0;
    left: 0;
    text-align: center;
  }
  
  footer a {
    color: lightblue;
    text-decoration: none;
    font-weight: bold;
  }
  
  footer a:hover {
    text-decoration: none;
    font-weight: bolder;
    color: lightblue;
  }
  
  form button {
    border: 1px solid black;
    padding: 5px;
    text-align: center;
  }
  
  .button-center {
    display: flex;
    justify-content: center;
  }