* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background-color: #f8fafc;
            color: #1a202c;
            line-height: 1.6;
            min-height: 100vh;
        }

        .container {
            max-width: 1100px;
            margin: 0 auto;
            padding: 20px;
        }

        /* Header */
        .header {
            background: white;
            border-radius: 12px;
            padding: 24px;
            margin-bottom: 24px;
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
            border: 1px solid #e2e8f0;
        }

        .header h1 {
            color: #2d3748;
            font-size: 1.875rem;
            font-weight: 700;
            margin-bottom: 16px;
            display: flex;
            align-items: center;
            gap: 12px;
        }

        .user-info {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            gap: 16px;
            padding: 16px;
            background: #f7fafc;
            border-radius: 8px;
            border: 1px solid #e2e8f0;
        }

        .user-icon {
            display: flex;
            align-items: center;
            gap: 8px;
            font-weight: 600;
            color: #2b6cb0;
        }

        .user-icon i {
            font-size: 1.25rem;
            background: #3182ce;
            color: white;
            padding: 8px;
            border-radius: 50%;
        }

        .date-info {
            background: #2d3748;
            color: white;
            padding: 8px 16px;
            border-radius: 6px;
            font-size: 0.875rem;
            font-weight: 500;
        }

        .logout-btn {
            background: #e53e3e;
            color: white;
            padding: 8px 16px;
            border-radius: 6px;
            text-decoration: none;
            font-size: 0.875rem;
            font-weight: 500;
            transition: background-color 0.2s;
        }

        .logout-btn:hover {
            background: #c53030;
        }

        /* Cards */
        .card {
            background: white;
            border-radius: 12px;
            padding: 24px;
            margin-bottom: 24px;
            box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1);
            border: 1px solid #e2e8f0;
            transition: box-shadow 0.2s ease;
        }

        .card:hover {
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }

        .card h3 {
            color: #2d3748;
            font-size: 1.25rem;
            font-weight: 600;
            margin-bottom: 16px;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        /* Media Section */
        .media-container {
            margin: 16px 0;
        }

        .video-container {
            position: relative;
            padding-bottom: 56.25%;
            height: 0;
            overflow: hidden;
            border-radius: 8px;
            background: #f7fafc;
        }

        .video-container iframe {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            border-radius: 8px;
        }

        /* Text Content */
        .text-section {
            background: #f7fafc;
            padding: 30px;
            border-radius: 12px;
            border-left: 4px solid #3182ce;
            font-size: 1.4rem;
            line-height: 1.8;
            margin: 16px 0;
            font-family: 'Georgia', 'Times New Roman', serif;
            font-weight: 500;
            letter-spacing: 0.5px;
            color: #2d3748;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
        }

        /* Recording Section */
        .recording-section {
            text-align: center;
            padding: 32px;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            border-radius: 12px;
            color: white;
        }

        .record-button {
            background: #e53e3e;
            color: white;
            border: none;
            border-radius: 50px;
            padding: 16px 32px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 8px;
            margin: 0 auto 16px;
            transition: all 0.2s ease;
            min-width: 200px;
        }

        .record-button:hover {
            background: #c53030;
            transform: translateY(-1px);
        }

        .record-button.recording {
            background: #c53030;
            animation: pulse 1.5s infinite;
        }

        .timer {
            font-size: 1.5rem;
            font-weight: 700;
            margin: 16px 0;
            color: #ffd700;
        }

        /* Questions */
        .question-item {
            background: #f7fafc;
            border-radius: 8px;
            padding: 20px;
            margin: 16px 0;
            border-left: 4px solid #805ad5;
        }

        .question-item h4 {
            color: #553c9a;
            font-size: 1.1rem;
            margin-bottom: 16px;
            font-weight: 600;
        }

        .question-record-btn {
            background: #805ad5;
            color: white;
            border: none;
            border-radius: 25px;
            padding: 12px 24px;
            font-size: 0.9rem;
            cursor: pointer;
            display: flex;
            align-items: center;
            gap: 8px;
            margin: 0 auto;
            transition: all 0.2s ease;
        }

        .question-record-btn:hover {
            background: #6b46c1;
        }

        .question-record-btn.recording {
            background: #6b46c1;
            animation: pulse 1.5s infinite;
        }

        /* Video Recording Styles */
        .video-preview {
            width: 100%;
            max-width: 400px;
            height: 300px;
            background: #000;
            border-radius: 8px;
            margin: 16px auto;
            display: none;
        }

        .video-item {
            background: #f7fafc;
            padding: 16px;
            border-radius: 8px;
            margin: 12px 0;
            border: 1px solid #e2e8f0;
            text-align: center;
        }

        .video-item video {
            width: 100%;
            max-width: 400px;
            height: 300px;
            border-radius: 8px;
            margin-top: 8px;
        }

        .question-record-btn.video {
            background: #805ad5;
            min-width: 200px;
        }

        .question-record-btn.video:hover {
            background: #6b46c1;
        }

        .question-record-btn.video.recording {
            background: #6b46c1;
            animation: pulse 1.5s infinite;
        }

        /* Vocabulary Quiz */
        .vocab-section {
            background: white;
            border-radius: 12px;
            padding: 24px;
            margin: 24px 0;
            border: 1px solid #e2e8f0;
        }

        .quiz-timer-container {
            background: #f7fafc;
            border: 2px solid #3182ce;
            border-radius: 8px;
            padding: 16px;
            margin: 16px 0;
            text-align: center;
        }

        .quiz-timer {
            font-size: 1.5rem;
            font-weight: 700;
            color: #2b6cb0;
            margin-bottom: 8px;
        }

        .timer-label {
            font-size: 0.875rem;
            color: #4a5568;
            font-weight: 500;
        }

        .timer-controls {
            display: flex;
            justify-content: center;
            gap: 12px;
            margin-top: 12px;
        }

        .timer-btn {
            background: #3182ce;
            color: white;
            border: none;
            border-radius: 6px;
            padding: 8px 16px;
            font-size: 0.875rem;
            cursor: pointer;
            transition: background-color 0.2s;
        }

        .timer-btn:hover {
            background: #2c5aa0;
        }

        .timer-btn:disabled {
            background: #a0aec0;
            cursor: not-allowed;
        }

        .quiz-content {
            display: none;
        }

        .quiz-content.active {
            display: block;
        }

        .vocab-item {
            background: #f7fafc;
            border-radius: 8px;
            padding: 20px;
            margin: 16px 0;
            border: 1px solid #e2e8f0;
        }

        .vocab-word {
            font-size: 1.125rem;
            font-weight: 600;
            color: #2d3748;
            margin-bottom: 12px;
        }

        .vocab-option {
            display: flex;
            align-items: center;
            padding: 10px 12px;
            margin: 6px 0;
            background: white;
            border: 1px solid #e2e8f0;
            border-radius: 6px;
            cursor: pointer;
            transition: all 0.2s ease;
        }

        .vocab-option:hover {
            background: #edf2f7;
            border-color: #cbd5e0;
        }

        .vocab-option input[type="radio"] {
            margin-right: 10px;
        }

        /* Wordbook */
        .wordbook-section {
            margin: 24px 0;
        }

        .collapsible-button {
            background: #3182ce;
            color: white;
            border: none;
            border-radius: 8px;
            padding: 16px 20px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            width: 100%;
            text-align: left;
            transition: background-color 0.2s;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .collapsible-button:hover {
            background: #2c5aa0;
        }

        .wordbook-content {
            background: white;
            border: 1px solid #e2e8f0;
            border-top: none;
            border-radius: 0 0 8px 8px;
            padding: 20px;
        }

        .wordbook-form {
            background: #f7fafc;
            padding: 20px;
            border-radius: 8px;
            margin-bottom: 20px;
            border: 1px solid #e2e8f0;
        }

        .today-words {
            margin-top: 20px;
        }

        .previous-days-section {
            margin-top: 20px;
        }

        .previous-days-button {
            background: #805ad5;
            color: white;
            border: none;
            border-radius: 8px;
            padding: 12px 16px;
            font-size: 0.9rem;
            font-weight: 600;
            cursor: pointer;
            width: 100%;
            text-align: left;
            transition: background-color 0.2s;
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 10px;
        }

        .previous-days-button:hover {
            background: #6b46c1;
        }

        .previous-days-content {
            background: #f7fafc;
            border: 1px solid #e2e8f0;
            border-radius: 8px;
            padding: 15px;
            margin-bottom: 15px;
            display: none;
        }

        .day-section {
            margin-bottom: 20px;
        }

        .day-header {
            background: #667eea;
            color: white;
            padding: 10px 15px;
            border-radius: 6px;
            font-weight: 600;
            margin-bottom: 10px;
            display: flex;
            justify-content: space-between;
            align-items: center;
            cursor: pointer;
            transition: background-color 0.2s;
        }

        .day-header:hover {
            background: #5a67d8;
        }

        .day-content {
            display: none;
            padding: 10px 0;
        }

        .word-item {
            background: white;
            border: 1px solid #e2e8f0;
            border-radius: 8px;
            padding: 16px;
            margin-bottom: 12px;
            border-left: 4px solid #3182ce;
        }

        .word-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 8px;
        }

        .word-title {
            font-size: 1.1rem;
            font-weight: 600;
            color: #2d3748;
        }

        .word-date {
            font-size: 0.8rem;
            color: #718096;
        }

        .word-meaning {
            color: #4a5568;
            line-height: 1.5;
        }

        .no-words {
            text-align: center;
            padding: 20px;
            color: #718096;
            font-style: italic;
        }

        /* Buttons */
        .btn {
            background: #3182ce;
            color: white;
            border: none;
            border-radius: 6px;
            padding: 10px 20px;
            font-size: 0.9rem;
            font-weight: 500;
            cursor: pointer;
            transition: background-color 0.2s;
            text-decoration: none;
            display: inline-block;
            margin: 4px;
        }

        .btn:hover {
            background: #2c5aa0;
        }

        .btn-success {
            background: #38a169;
        }

        .btn-success:hover {
            background: #2f855a;
        }

        /* Navigation */
        .navigation {
            text-align: center;
            margin: 32px 0;
            display: flex;
            justify-content: center;
            gap: 16px;
            flex-wrap: wrap;
        }

        /* Animations */
        @keyframes pulse {
            0%, 100% {
                opacity: 1;
            }
            50% {
                opacity: 0.8;
            }
        }

        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(10px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .card {
            animation: fadeIn 0.5s ease-out;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .container {
                padding: 16px;
            }

            .user-info {
                flex-direction: column;
                text-align: center;
            }

            .card {
                padding: 20px;
            }

            .record-button {
                min-width: auto;
                width: 100%;
                max-width: 280px;
            }

            .navigation {
                flex-direction: column;
                align-items: center;
            }

            .timer-controls {
                flex-direction: column;
                align-items: center;
            }

            .text-content {
                font-size: 1.2rem;
                padding: 20px;
            }

            .video-preview, .video-item video {
                max-width: 100%;
                height: 200px;
            }
        }

        /* Status Messages */
        .status {
            padding: 12px 16px;
            border-radius: 6px;
            margin: 16px 0;
            text-align: center;
            font-weight: 500;
        }

        .status.success {
            background: #c6f6d5;
            color: #22543d;
            border: 1px solid #9ae6b4;
        }

        .status.error {
            background: #fed7d7;
            color: #742a2a;
            border: 1px solid #feb2b2;
        }

        .audio-item {
            background: #f7fafc;
            padding: 16px;
            border-radius: 8px;
            margin: 12px 0;
            border: 1px solid #e2e8f0;
        }

        audio {
            width: 100%;
            margin-top: 8px;
        }

        /* Form Elements */
        input[type="text"], textarea {
            width: 100%;
            padding: 10px 12px;
            border: 1px solid #e2e8f0;
            border-radius: 6px;
            font-size: 0.9rem;
            margin: 8px 0;
            transition: border-color 0.2s;
            box-sizing: border-box;
        }

        input[type="text"]:focus, textarea:focus {
            outline: none;
            border-color: #3182ce;
            box-shadow: 0 0 0 3px rgba(49, 130, 206, 0.1);
        }

        textarea {
            min-height: 80px;
            resize: vertical;
        }

        /* Notification */
        .notification {
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 15px 20px;
            border-radius: 8px;
            color: white;
            font-weight: 600;
            z-index: 1000;
            transform: translateX(400px);
            transition: transform 0.3s ease;
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
        }

        .notification.success {
            background: #38a169;
        }

        .notification.error {
            background: #e53e3e;
        }

        .notification.show {
            transform: translateX(0);
        }