* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    
    body {
      font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      min-height: 100vh;
      padding: 20px;
    }
    
    #app {
      max-width: 1200px;
      margin: 0 auto;
      background: white;
      border-radius: 20px;
      box-shadow: 0 20px 60px rgba(0,0,0,0.3);
      overflow: hidden;
    }
    
    header {
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      color: white;
      padding: 30px;
      text-align: center;
    }
    
    header h1 {
      font-size: 2.5em;
      margin-bottom: 10px;
    }
    
    header p {
      font-size: 1.2em;
      opacity: 0.9;
    }
    
    main {
      padding: 30px;
    }
    
    #upload-section {
      background: #f7f9fc;
      padding: 30px;
      border-radius: 10px;
      margin-bottom: 30px;
      text-align: center;
    }
    
    #upload-section h2 {
      color: #333;
      margin-bottom: 10px;
    }
    
    #upload-section p {
      color: #666;
      margin-bottom: 20px;
    }
    
    input[type="file"] {
      display: block;
      margin: 20px auto;
      padding: 10px;
      border: 2px dashed #667eea;
      border-radius: 5px;
      background: white;
      cursor: pointer;
    }
    
    button {
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      color: white;
      border: none;
      padding: 12px 30px;
      border-radius: 25px;
      font-size: 16px;
      cursor: pointer;
      transition: transform 0.2s;
    }
    
    button:hover {
      transform: translateY(-2px);
    }
    
    #chat-section {
      background: #f7f9fc;
      padding: 20px;
      border-radius: 10px;
      margin-bottom: 30px;
    }
    
    #messages {
      height: 400px;
      overflow-y: auto;
      padding: 20px;
      background: white;
      border-radius: 10px;
      margin-bottom: 20px;
    }
    
    .message {
      margin-bottom: 15px;
      padding: 10px 15px;
      border-radius: 10px;
    }
    
    .message.user {
      background: #e3f2fd;
      margin-left: 20%;
      text-align: right;
    }
    
    .message.assistant {
      background: #f3e5f5;
      margin-right: 20%;
    }
    
    #input-area {
      display: flex;
      gap: 10px;
    }
    
    #message-input {
      flex: 1;
      padding: 12px;
      border: 2px solid #e0e0e0;
      border-radius: 25px;
      font-size: 16px;
    }
    
    #library-section {
      background: #f7f9fc;
      padding: 20px;
      border-radius: 10px;
    }
    
    #library-list {
      display: grid;
      grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
      gap: 15px;
      margin-top: 15px;
    }
    
    .book-card {
      background: white;
      padding: 15px;
      border-radius: 10px;
      cursor: pointer;
      transition: transform 0.2s;
    }
    
    .book-card:hover {
      transform: translateY(-3px);
      box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    }
    
    .book-title {
      font-weight: bold;
      color: #333;
      margin-bottom: 5px;
    }
    
    .book-author {
      color: #666;
      font-size: 0.9em;
    }
    
    .hero-section {
      background: #f7f9fc;
      padding: 40px;
      border-radius: 10px;
      margin-bottom: 30px;
    }
    
    .hero-section h2 {
      color: #333;
      font-size: 2em;
      margin-bottom: 20px;
    }
    
    .benefits {
      display: grid;
      grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
      gap: 20px;
      margin-top: 30px;
    }
    
    .benefit {
      background: white;
      padding: 20px;
      border-radius: 10px;
      box-shadow: 0 2px 10px rgba(0,0,0,0.05);
    }
    
    .benefit h3 {
      color: #667eea;
      margin-bottom: 10px;
    }
    
    .example-uses {
      margin-top: 30px;
      background: white;
      padding: 20px;
      border-radius: 10px;
    }
    
    .example-uses h3 {
      color: #333;
      margin-bottom: 15px;
    }
    
    .example-uses ul {
      list-style: none;
      padding: 0;
    }
    
    .example-uses li {
      padding: 10px 0;
      border-bottom: 1px solid #e0e0e0;
    }
    
    .example-uses li:last-child {
      border-bottom: none;
    }
    
    .how-it-works {
      background: #f7f9fc;
      padding: 40px;
      border-radius: 10px;
      margin: 30px 0;
    }
    
    .how-it-works h2 {
      color: #333;
      text-align: center;
      margin-bottom: 30px;
    }
    
    .how-it-works ol {
      list-style: none;
      counter-reset: step-counter;
      padding: 0;
    }
    
    .how-it-works li {
      counter-increment: step-counter;
      margin-bottom: 30px;
      padding-left: 50px;
      position: relative;
    }
    
    .how-it-works li::before {
      content: counter(step-counter);
      position: absolute;
      left: 0;
      top: 0;
      background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
      color: white;
      width: 35px;
      height: 35px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: bold;
    }
    
    .testimonials {
      padding: 40px;
      background: white;
      border-radius: 10px;
      margin-bottom: 30px;
    }
    
    .testimonials h2 {
      text-align: center;
      color: #333;
      margin-bottom: 30px;
    }
    
    .testimonial {
      background: #f7f9fc;
      padding: 20px;
      border-radius: 10px;
      margin-bottom: 20px;
      border-left: 4px solid #667eea;
    }
    
    .testimonial p {
      font-style: italic;
      color: #555;
      margin-bottom: 10px;
    }
    
    .testimonial cite {
      color: #667eea;
      font-weight: bold;
    }
    
    footer {
      background: #333;
      color: white;
      padding: 30px;
      text-align: center;
      margin-top: 50px;
      border-radius: 0 0 20px 20px;
    }
    
    footer nav {
      margin-top: 15px;
    }
    
    footer a {
      color: white;
      text-decoration: none;
      margin: 0 10px;
    }
    
    footer a:hover {
      color: #667eea;
    }