style.css

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

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
    overflow-x: hidden;
}

.app-container {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    max-width: 100vw;
}

/* Header Styles */
.header {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.2);
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
}

.header-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 1rem;
}

.logo {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.logo i {
    font-size: 2rem;
    color: #667eea;
}

.logo h1 {
    font-size: 1.5rem;
    font-weight: 700;
    color: #2d3748;
}

.device-toggle {
    display: flex;
    align-items: center;
    gap: 1rem;
    flex-wrap: wrap;
}

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

.device-btn {
    background: #f7fafc;
    border: 2px solid #e2e8f0;
    border-radius: 8px;
    padding: 0.25rem;
    display: flex;
    gap: 0.25rem;
    cursor: pointer;
    transition: all 0.2s ease;
}

.device-btn:hover {
    border-color: #cbd5e0;
}

.device-option {
    padding: 0.5rem 1rem;
    border-radius: 6px;
    font-size: 0.875rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
    color: #4a5568;
}

.device-option.active {
    background: #667eea;
    color: white;
    box-shadow: 0 2px 4px rgba(102, 126, 234, 0.3);
}

.status-indicator {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.5rem 1rem;
    background: #f7fafc;
    border-radius: 6px;
    border: 1px solid #e2e8f0;
}

.status-indicator i {
    color: #f56565;
    font-size: 0.5rem;
    animation: pulse 2s infinite;
}

.status-indicator.ready i {
    color: #48bb78;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

.credit {
    text-align: center;
    padding: 0.75rem 2rem;
    background: rgba(255, 255, 255, 0.1);
    font-size: 0.875rem;
    color: #4a5568;
}

.credit a {
    color: #667eea;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s ease;
}

.credit a:hover {
    color: #5a67d8;
    text-decoration: underline;
}

/* Main Content */
.main-content {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 2rem;
}

.chat-container {
    background: white;
    border-radius: 16px;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.15);
    width: 100%;
    max-width: 800px;
    height: 600px;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

/* Messages Container */
.messages-container {
    flex: 1;
    overflow-y: auto;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.welcome-message {
    text-align: center;
    padding: 3rem 2rem;
    background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
    border-radius: 12px;
    border: 2px dashed #cbd5e0;
}

.welcome-icon {
    font-size: 3rem;
    color: #667eea;
    margin-bottom: 1rem;
}

.welcome-message h2 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 0.5rem;
}

.welcome-message p {
    color: #4a5568;
    line-height: 1.6;
}

/* Message Styles */
.message {
    display: flex;
    gap: 1rem;
    animation: fadeInUp 0.3s ease;
}

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

.message-avatar {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
    flex-shrink: 0;
}

.message.user .message-avatar {
    background: #667eea;
    color: white;
}

.message.assistant .message-avatar {
    background: #48bb78;
    color: white;
}

.message-content {
    flex: 1;
    min-width: 0;
}

.message-header {
    margin-bottom: 0.5rem;
}

.message-role {
    font-size: 0.875rem;
    font-weight: 600;
    color: #4a5568;
}

.message-text {
    background: #f7fafc;
    padding: 1rem 1.25rem;
    border-radius: 12px;
    line-height: 1.6;
    color: #2d3748;
    border: 1px solid #e2e8f0;
}

.message.user .message-text {
    background: #667eea;
    color: white;
    margin-left: 2rem;
}

.message.assistant .message-text {
    background: #f7fafc;
    margin-right: 2rem;
}

/* Input Container */
.input-container {
    border-top: 1px solid #e2e8f0;
    padding: 1.5rem;
    background: #fafafa;
}

.input-wrapper {
    display: flex;
    gap: 1rem;
    align-items: flex-end;
}

#messageInput {
    flex: 1;
    padding: 1rem 1.25rem;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    resize: none;
    font-family: inherit;
    font-size: 1rem;
    line-height: 1.5;
    background: white;
    transition: border-color 0.2s ease;
    min-height: 48px;
    max-height: 120px;
}

#messageInput:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

#messageInput:disabled {
    background: #f7fafc;
    color: #a0aec0;
    cursor: not-allowed;
}

.send-button {
    width: 48px;
    height: 48px;
    border: none;
    border-radius: 12px;
    background: #667eea;
    color: white;
    font-size: 1.1rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.send-button:hover:not(:disabled) {
    background: #5a67d8;
    transform: translateY(-1px);
    box-shadow: 0 4px 12px rgba(102, 126, 234, 0.4);
}

.send-button:disabled {
    background: #cbd5e0;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.input-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-top: 0.75rem;
    font-size: 0.875rem;
    color: #4a5568;
}

.model-info {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.char-count {
    font-weight: 500;
}

/* Loading Overlay */
.loading-overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(5px);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.loading-content {
    text-align: center;
    max-width: 400px;
    padding: 2rem;
}

.loading-spinner {
    margin-bottom: 2rem;
}

.spinner {
    width: 60px;
    height: 60px;
    border: 4px solid #e2e8f0;
    border-top: 4px solid #667eea;
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin: 0 auto;
}

@keyframes spin {
    0% { transform: rotate(0deg); }
    100% { transform: rotate(360deg); }
}

.loading-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 0.5rem;
}

.loading-content p {
    color: #4a5568;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.progress-bar {
    width: 100%;
    height: 8px;
    background: #e2e8f0;
    border-radius: 4px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, #667eea, #48bb78);
    width: 0%;
    transition: width 0.3s ease;
}

/* Error Modal */
.error-modal {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(0, 0, 0, 0.5);
    display: flex;
    justify-content: center;
    align-items: center;
    z-index: 1000;
}

.error-content {
    background: white;
    padding: 2rem;
    border-radius: 16px;
    text-align: center;
    max-width: 400px;
    margin: 1rem;
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.2);
}

.error-icon {
    font-size: 3rem;
    color: #f56565;
    margin-bottom: 1rem;
}

.error-content h3 {
    font-size: 1.5rem;
    font-weight: 600;
    color: #2d3748;
    margin-bottom: 1rem;
}

.error-content p {
    color: #4a5568;
    margin-bottom: 2rem;
    line-height: 1.6;
}

.retry-button {
    background: #667eea;
    color: white;
    border: none;
    padding: 0.75rem 2rem;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 500;
    cursor: pointer;
    transition: background 0.2s ease;
}

.retry-button:hover {
    background: #5a67d8;
}

/* Toast Notifications */
.toast {
    position: fixed;
    bottom: 2rem;
    right: 2rem;
    background: #2d3748;
    color: white;
    padding: 1rem 1.5rem;
    border-radius: 8px;
    font-size: 0.875rem;
    font-weight: 500;
    transform: translateX(400px);
    transition: transform 0.3s ease;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
}

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

/* Responsive Design */
@media (max-width: 768px) {
    .header-content {
        padding: 0 1rem;
        flex-direction: column;
        text-align: center;
    }

    .logo h1 {
        font-size: 1.25rem;
    }

    .device-toggle {
        justify-content: center;
    }

    .main-content {
        padding: 1rem;
    }

    .chat-container {
        height: calc(100vh - 200px);
    }

    .messages-container {
        padding: 1rem;
    }

    .input-container {
        padding: 1rem;
    }

    .message.user .message-text {
        margin-left: 1rem;
    }

    .message.assistant .message-text {
        margin-right: 1rem;
    }

    .toast {
        left: 1rem;
        right: 1rem;
        transform: translateY(100px);
    }

    .toast.show {
        transform: translateY(0);
    }
}

@media (max-width: 480px) {
    .header {
        padding: 0.75rem 0;
    }

    .device-toggle {
        flex-direction: column;
        gap: 0.75rem;
    }

    .device-btn {
        width: 100%;
        justify-content: center;
    }

    .logo {
        flex-direction: column;
        gap: 0.5rem;
    }

    .logo i {
        font-size: 1.5rem;
    }

    .logo h1 {
        font-size: 1.125rem;
    }

    .input-footer {
        flex-direction: column;
        gap: 0.5rem;
        align-items: flex-start;
    }
}

/* Scrollbar Styling */
.messages-container::-webkit-scrollbar {
    width: 6px;
}

.messages-container::-webkit-scrollbar-track {
    background: #f1f1f1;
}

.messages-container::-webkit-scrollbar-thumb {
    background: #cbd5e0;
    border-radius: 3px;
}

.messages-container::-webkit-scrollbar-thumb:hover {
    background: #a0aec0;
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
    * {
        animation-duration: 0.01ms !important;
        animation-iteration-count: 1 !important;
        transition-duration: 0.01ms !important;
    }
}

/* Focus styles for accessibility */
button:focus,
textarea:focus {
    outline: 2px solid #667eea;
    outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
    .message-text {
        border-width: 2px;
    }
    
    .device-btn {
        border-width: 2px;
    }
}

The application is now complete with a modern, responsive chatbot interface that uses the Gemma AI model via transformers.js. Here are the key features:

## Key Features:

1. **Modern UI Design**: Clean, professional interface with gradient backgrounds and smooth animations
2. **Responsive Layout**: Works perfectly on desktop, tablet, and mobile devices
3. **Real-time Streaming**: Uses TextStreamer for real-time response generation
4. **Device Toggle**: Option to switch between CPU and WebGPU execution
5. **Smart Input**: Auto-resizing textarea with character counter
6. **Loading States**: Comprehensive loading overlay with progress indicator
7. **Error Handling**: User-friendly error modal with retry functionality
8. **Accessibility**: Proper focus styles, reduced motion support, and high contrast compatibility
9. **Professional Features**: Welcome message, typing indicators, toast notifications

## How to Use:

1. **Loading**: The app automatically loads the Gemma model on startup
2. **Device Selection**: Toggle between CPU and GPU execution based on your browser's WebGPU support
3. **Chatting**: Type messages and press Enter (or Ctrl+Enter for new lines) to send
4. **Streaming**: Watch responses appear in real-time as they're generated

The application is production-ready and includes all the transformers.js functionality you specified, including the TextStreamer for real-time response generation.