/* Reset & Base */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
  }
  
  body {
    background-color: #121212;
    color: #e0e0e0;
    font-family: 'Lucida Sans', 'Lucida Grande', 'Verdana', sans-serif;
    line-height: 1.6;
    text-align: justify;
    margin: 30px;;
    padding: 0;
    overflow-x: hidden; 
  }
  
  /* Content wrapper */
  .content-container {
    max-width: 800px;
    margin: 40px auto;
    padding: 0 1em;
  }
  
  /* Top nav */
  .topnav {
    background-color: transparent;
    overflow: hidden;
    padding: 10px;
    text-align: center;
  }
  
  .topnav a {
    color: white;
    text-decoration: none;
    padding: 14px 20px;
    display: inline-block;
  }
  
  .topnav a.active {
    background-color: transparent;
    text-align: center;
  }
  .topnav a:visited{
    color: yellow;
  }
  
  .topnav a:hover {
    background-color: #ddd;
    color: black;
  }
  
  /* Typography */
  h1, h2, h5 {
    text-align: center;
    margin: 1em 0;
  }
  @media only screen and (max-width: 600px) {
    .chapters {
      font-size: 12px;
    }
  }
  p {
    font-size: 20px;
    margin-bottom: 1em;
  }
  
  /* Back to Top Button */
  #backToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background-color: #333;
    color: white;
    padding: 0.6em 0.8em;
    font-size: 1.5em;
    border-radius: 50%;
    text-decoration: none;
    text-align: center;
    opacity: 0.7;
    z-index: 1000;
    transition: opacity 0.3s, background-color 0.3s;
  }
  
  #backToTop:hover {
    opacity: 1;
    background-color: #000;
  }
  

  @media (max-width: 600px) {
    .content-container {
      margin: 20px auto;
      padding: 0 1em;
    }
  
    p {
      font-size: 18px;
    }
  
    .topnav {
      padding: 5px;
    }
  
    .topnav a {
      margin: 0;
      padding: 10px;
      display: block;
      text-align: center;
    }
  
    h1, h2, h5 {
      text-align: center;
    }
  }
  
  @media (max-width: 600px) {
    #backToTop {
      position: fixed;
      bottom: 30px;
      right: 30px;
      width: 40px;
      height: 40px;
      text-indent: -9999px; 
      display: inline-block;
      background: transparent;
    }
  
    #backToTop::before {
      content: '';
      position: absolute;
      left: 50%;
      top: 50%;
      transform: translate(-50%, -50%);
      border-left: 10px solid transparent;
      border-right: 10px solid transparent;
      border-bottom: 15px solid #7b86d5; 
      width: 0;
      height: 0;
    }
  }