* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            color: #333;
            background-color: #f5f5f5;
            padding: 1rem;
            line-height: 1.7;
        }

        .container {
            max-width: 700px;
            margin: 0 auto 0 320px;
        }

        h1 {
            font-size: 28px;
            font-weight: 500;
            margin-bottom: 0.5rem;
            text-align: center;
            color: #333;
        }

        .subtitle {
            text-align: center;
            color: #666;
            margin-bottom: 1.5rem;
            font-size: 14px;
        }

        .selector-group {
            margin-bottom: 2rem;
            display: flex;
            gap: 0.5rem;
            align-items: center;
        }
        
        .selector-group label {
            font-size: 14px;
            font-weight: 500;
            color: #333;
        }
        
        select {
            flex: 1;
            padding: 0.6rem;
            font-size: 14px;
            border: 1px solid #ddd;
            border-radius: 8px;
            background-color: white;
            color: #333;
            font-family: inherit;
            cursor: pointer;
        }
        
        select:focus {
            outline: none;
            border-color: #4CAF50;
        }
        
        .exercise {
            background-color: white;
            border: 1px solid #ddd;
            border-radius: 12px;
            padding: 1.5rem;
            margin-bottom: 2rem;
            animation: slideIn 0.3s ease-out;
        }
        
        @keyframes slideIn {
            from {
                opacity: 0;
                transform: translateY(10px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }
        
        .exercise-title {
            font-size: 14px;
            font-weight: 500;
            color: #666;
            text-transform: uppercase;
            letter-spacing: 0.5px;
            margin-bottom: 1rem;
        }
        
        .exercise-description {
            font-size: 13px;
            color: #666;
            margin-bottom: 1.5rem;
            font-style: italic;
        }
        
        .sentence {
            margin-bottom: 1.2rem;
            font-size: 16px;
            line-height: 1.8;
        }
        
        input[type="text"] {
            background-color: #f9f9f9;
            border: 2px solid #ddd;
            border-radius: 4px;
            padding: 0.4rem 0.6rem;
            font-size: 15px;
            color: #333;
            font-family: inherit;
            min-width: 70px;
            max-width: 150px;
            transition: border-color 0.2s;
        }
        
        input[type="text"]:focus {
            outline: none;
            border-color: #4CAF50;
        }
        
        input.correct {
            background-color: #e8f5e9;
            border-color: #4CAF50;
            color: #2e7d32;
        }
        
        input.incorrect {
            background-color: #ffebee;
            border-color: #f44336;
            color: #c62828;
        }
        
        input.empty {
            border-color: #f44336;
        }
        
        .button-group {
            display: flex;
            gap: 1rem;
            margin-top: 1.5rem;
        }
        
        button {
            flex: 1;
            padding: 0.7rem 1.5rem;
            font-size: 15px;
            font-weight: 500;
            border: none;
            border-radius: 8px;
            cursor: pointer;
            transition: all 0.2s;
            font-family: inherit;
        }
        
        .btn-submit {
            background-color: #4CAF50;
            color: white;
        }
        
        .btn-submit:hover {
            opacity: 0.9;
        }
        
        .btn-submit:disabled {
            opacity: 0.6;
            cursor: not-allowed;
        }
        
        .feedback-container {
            margin-top: 2rem;
            display: none;
            animation: fadeIn 0.4s ease-out;
        }
        
        .feedback-container.show {
            display: block;
        }
        
        @keyframes fadeIn {
            from {
                opacity: 0;
            }
            to {
                opacity: 1;
            }
        }
        
        .beaver-container {
            display: flex;
            gap: 1.5rem;
            align-items: flex-start;
        }

        .beaver
        {
            text-align:center;
        }        
       
        .feedback-message {
            flex: 1;
            background: linear-gradient(135deg, #f9f9f9 0%, white 100%);
            border: 2px solid #ddd;
            border-radius: 12px;
            padding: 1.5rem;
        }
        
        .score-display {
            font-size: 32px;
            font-weight: 500;
            color: #333;
            margin-bottom: 0.5rem;
        }
        
        
        .feedback-text {
            font-size: 15px;
            line-height: 1.6;
            color: #333;
        }
        
       .accents-toolbar {
            background-color: #f5f5f5;
            border: 1px solid #ddd;
            border-radius: 8px;
            padding: 0.8rem;
            margin-bottom: 1.5rem;
            display: flex;
            flex-wrap: wrap;
            gap: 0.4rem;
            align-items: center;
            font-size: 14px;
            color: #666;
        }
        
        .accents-label {
            font-weight: 500;
            margin-right: 0.5rem;
            white-space: nowrap;
        }
        
        .accent-char {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            min-width: 32px;
            height: 32px;
            background-color: white;
            border: 1px solid #ccc;
            border-radius: 4px;
            cursor: pointer;
            font-size: 15px;
            font-weight: 500;
            color: #333;
            transition: all 0.2s;
            user-select: none;
        }
        
        .accent-char:hover {
            background-color: #e8f5e9;
            border-color: #4CAF50;
            color: #2e7d32;
        }
        
        .accent-char:active {
            transform: scale(0.95);
        }
        
    #indexContainer {
      position: fixed;
      left: 20px;
      top: 20px;
      width: 300px;
      max-height: 90vh;
      background: white;
      border-radius: 15px;
      padding: 20px;
		border:1px solid #ccc;
      overflow-y: auto;
      z-index: 1000;
    }

    .index-title {
      font-size: 24px;
      font-weight: bold;
      color: #667eea;
      margin-bottom: 20px;
      text-align: center;
    }

    .chapter {
      margin-bottom: 20px;
    }

    .chapter-name {
      font-size: 16px;
      font-weight: bold;
      color: #764ba2;
      margin-bottom: 10px;
      padding: 10px;
      background: #f0f0f0;
      border-radius: 8px;
    }

    .file-list {
      list-style: none;
      margin-left: 0;
    }

    .file-item {
      margin-bottom: 8px;
    }

    .file-title {
      display: block;
      padding: 8px 12px;
      background: #e8f4f8;
      border-radius: 6px;
      color: #667eea;
      font-size: 14px;
      cursor: pointer;
      transition: all 0.3s ease;
      border-left: 4px solid #667eea;
    }

    .file-title:hover {
      background: #d0e8f0;
      transform: translateX(5px);
      border-left-color: #764ba2;
    }

    .file-title:active { background: #b8dce8; }