style.css

body {
    font-family: Georgia, Times, "Times New Roman", serif;
    max-width: 800px;
    margin: 0 auto;
    font-size: 18px;
    padding-left: 20%;
    padding-right: 50px;
    color: #111;
  }
  
  h1,
  h2,
  h3,
  h4,
  h5,
  h6 {
    margin-top: 5em;
    margin-bottom: 2em;
  }
  
  blockquote {
    margin-left: 3em;
    margin-right: 3em;
  }
  
  header {
    padding: 40% 0;
  }
  
  #TOC {
    position: fixed;
    left: 0;
    top: 0;
    overflow-y: scroll;
    -webkit-overflow-scrolling: touch;
    height: 100%;
    background: #fafafa;
    max-width: 15%;
    font-family: Helvetica Neue, Helvetica, Arial, sans-serif;
    font-size: 15px;
    line-height: 30px;
  }
  
  #TOC::-webkit-scrollbar {
    width: 8px;
  }
  
  #TOC::-webkit-scrollbar-track {
    background-color: #ececec;
  }
  
  #TOC::-webkit-scrollbar-thumb {
    background-color: #b0b0b0;
    border-radius: 8px;
  }
  
  #TOC > ul {
    padding-right: 10px;
  }
  
  #TOC ul {
    list-style: none;
    padding-left: 20px;
  }
  
  #TOC ul li a {
    text-decoration: none;
    color: #364149;
    display: block;
  }
  
  #TOC ul li a:hover {
    color: #008cff;
  }
  
  figure {
    text-align: center;
  }
  
  figure p {
    text-align: center;
    font-style: italic;
  }
  
  figure img {
    width: 100%;
  }