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

:root {
--primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
--bg-primary: #ffffff;
--bg-secondary: #f5f5f7;
--bg-tertiary: #e8e8ed;
--text-primary: #1d1d1f;
--text-secondary: #86868b;
--user-msg-bg: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
--ai-msg-bg: #f5f5f7;
--border-color: #d2d2d7;
--shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
--shadow-hover: 0 8px 30px rgba(0, 0, 0, 0.12);
}

body {
font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
background: var(--bg-secondary);
color: var(--text-primary);
line-height: 1.6;
overflow: hidden;
}

.container {
max-width: 1200px;
margin: 0 auto;
height: 100vh;
display: flex;
flex-direction: column;
background: var(--bg-primary);
}

.header {
background: var(--bg-primary);
border-bottom: 1px solid var(--border-color);
padding: 1rem 2rem;
backdrop-filter: blur(20px);
-webkit-backdrop-filter: blur(20px);
}

.header-content {
display: flex;
justify-content: space-between;
align-items: center;
}

.logo {
display: flex;
align-items: center;
gap: 1rem;
}

.logo h1 {
font-size: 1.5rem;
font-weight: 600;
background: var(--primary-gradient);
-webkit-background-clip: text;
-webkit-text-fill-color: transparent;
background-clip: text;
}

.built-with {
color: var(--text-secondary);
text-decoration: none;
font-size: 0.875rem;
padding: 0.5rem 1rem;
border-radius: 20px;
transition: all 0.3s ease;
}

.built-with:hover {
background: var(--bg-secondary);
color: var(--text-primary);
}

.chat-container {
flex: 1;
display: flex;
flex-direction: column;
overflow: hidden;
position: relative;
}

/* Loading Screen */
.loading-screen {
position: absolute;
top: 0;
left: 0;
right: 0;
bottom: 0;
background: var(--bg-primary);
display: flex;
align-items: center;
justify-content: center;
z-index: 1000;
}

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

.spinner {
width: 60px;
height: 60px;
margin: 0 auto 2rem;
border: 4px solid var(--bg-tertiary);
border-top: 4px solid #667eea;
border-radius: 50%;
animation: spin 1s linear infinite;
}

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

.loading-content h2 {
font-size: 1.5rem;
margin-bottom: 0.5rem;
font-weight: 600;
}

.loading-content p {
color: var(--text-secondary);
margin-bottom: 1.5rem;
}

.progress-bar {
width: 100%;
height: 4px;
background: var(--bg-tertiary);
border-radius: 2px;
overflow: hidden;
margin-bottom: 1rem;
}

.progress-fill {
height: 100%;
background: var(--primary-gradient);
width: 0%;
transition: width 0.3s ease;
}

.loading-details {
font-size: 0.75rem;
color: var(--text-secondary);
min-height: 1.5rem;
}

/* Chat Interface */
.chat-interface {
flex: 1;
display: flex;
flex-direction: column;
overflow: hidden;
}

.messages-container {
flex: 1;
overflow-y: auto;
padding: 2rem;
scroll-behavior: smooth;
}

.messages-container::-webkit-scrollbar {
width: 8px;
}

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

.messages-container::-webkit-scrollbar-thumb {
background: var(--border-color);
border-radius: 4px;
}

.messages-container::-webkit-scrollbar-thumb:hover {
background: var(--text-secondary);
}

.welcome-message {
text-align: center;
padding: 3rem 1rem;
max-width: 600px;
margin: 0 auto;
}

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

.welcome-message p {
color: var(--text-secondary);
margin-bottom: 2rem;
}

.suggestions {
display: flex;
flex-wrap: wrap;
gap: 0.75rem;
justify-content: center;
}

.suggestion-btn {
background: var(--bg-secondary);
border: 1px solid var(--border-color);
padding: 0.75rem 1.25rem;
border-radius: 20px;
cursor: pointer;
font-size: 0.875rem;
transition: all 0.3s ease;
color: var(--text-primary);
}

.suggestion-btn:hover {
background: var(--bg-tertiary);
transform: translateY(-2px);
box-shadow: var(--shadow);
}

.message {
display: flex;
gap: 1rem;
margin-bottom: 1.5rem;
animation: fadeIn 0.3s ease;
}

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

.message.user {
flex-direction: row-reverse;
}

.message-avatar {
width: 36px;
height: 36px;
border-radius: 50%;
display: flex;
align-items: center;
justify-content: center;
flex-shrink: 0;
font-size: 1.25rem;
}

.message.user .message-avatar {
background: var(--user-msg-bg);
color: white;
}

.message.ai .message-avatar {
background: var(--bg-secondary);
}

.message-content {
max-width: 70%;
padding: 1rem 1.25rem;
border-radius: 20px;
word-wrap: break-word;
}

.message.user .message-content {
background: var(--user-msg-bg);
color: white;
border-bottom-right-radius: 4px;
}

.message.ai .message-content {
background: var(--ai-msg-bg);
border-bottom-left-radius: 4px;
}

.message-content p {
margin: 0;
white-space: pre-wrap;
}

.typing-indicator {
display: flex;
gap: 0.25rem;
padding: 0.5rem 0;
}

.typing-dot {
width: 8px;
height: 8px;
border-radius: 50%;
background: var(--text-secondary);
animation: typing 1.4s infinite;
}

.typing-dot:nth-child(2) {
animation-delay: 0.2s;
}

.typing-dot:nth-child(3) {
animation-delay: 0.4s;
}

@keyframes typing {
0%, 60%, 100% {
opacity: 0.3;
transform: translateY(0);
}
30% {
opacity: 1;
transform: translateY(-4px);
}
}

/* Input Container */
.input-container {
padding: 1.5rem 2rem 2rem;
background: var(--bg-primary);
border-top: 1px solid var(--border-color);
}

.input-wrapper {
display: flex;
gap: 0.75rem;
background: var(--bg-secondary);
border-radius: 24px;
padding: 0.75rem 1rem;
border: 2px solid transparent;
transition: all 0.3s ease;
}

.input-wrapper:focus-within {
border-color: #667eea;
background: var(--bg-primary);
box-shadow: var(--shadow);
}

#userInput {
flex: 1;
border: none;
background: transparent;
font-size: 1rem;
resize: none;
outline: none;
font-family: inherit;
max-height: 120px;
color: var(--text-primary);
}

#userInput::placeholder {
color: var(--text-secondary);
}

.send-btn {
width: 40px;
height: 40px;
border-radius: 50%;
border: none;
background: var(--primary-gradient);
color: white;
cursor: pointer;
display: flex;
align-items: center;
justify-content: center;
transition: all 0.3s ease;
flex-shrink: 0;
}

.send-btn:hover:not(:disabled) {
transform: scale(1.05);
box-shadow: var(--shadow);
}

.send-btn:disabled {
opacity: 0.5;
cursor: not-allowed;
}

.input-info {
display: flex;
justify-content: space-between;
margin-top: 0.5rem;
padding: 0 0.5rem;
font-size: 0.75rem;
color: var(--text-secondary);
}

.model-info {
font-weight: 500;
}

/* Responsive */
@media (max-width: 768px) {
.header {
padding: 1rem;
}

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

.messages-container {
padding: 1rem;
}

.message-content {
max-width: 85%;
}

.input-container {
padding: 1rem;
}

.suggestions {
flex-direction: column;
}

.suggestion-btn {
width: 100%;
}
}

=== app.js ===
import { pipeline, TextStreamer } from "https://cdn.jsdelivr.net/npm/@huggingface/transformers@3.1.2";

class ChatApp {
constructor() {
this.generator = null;
this.messages = [
{ role: "system", content: "You are a helpful, friendly, and knowledgeable AI assistant. Provide clear, concise, and
accurate responses." }
];
this.isGenerating = false;
this.currentStreamingMessage = null;

this.initElements();
this.attachEventListeners();
this.initModel();
}

initElements() {
this.loadingScreen = document.getElementById('loadingScreen');
this.chatInterface = document.getElementById('chatInterface');
this.messagesContainer = document.getElementById('messagesContainer');
this.userInput = document.getElementById('userInput');
this.sendBtn = document.getElementById('sendBtn');
this.charCount = document.getElementById('charCount');
this.loadingStatus = document.getElementById('loadingStatus');
this.progressFill = document.getElementById('progressFill');
this.loadingDetails = document.getElementById('loadingDetails');
}

attachEventListeners() {
this.sendBtn.addEventListener('click', () => this.handleSend());
this.userInput.addEventListener('keydown', (e) => {
if (e.key === 'Enter' && !e.shiftKey) {
e.preventDefault();
this.handleSend();
}
});

this.userInput.addEventListener('input', () => {
this.updateCharCount();
this.autoResizeTextarea();
this.updateSendButton();
});

// Suggestion buttons
document.addEventListener('click', (e) => {
if (e.target.classList.contains('suggestion-btn')) {
const prompt = e.target.dataset.prompt;
this.userInput.value = prompt;
this.updateCharCount();
this.updateSendButton();
this.userInput.focus();
}
});
}

async initModel() {
try {
this.updateLoadingStatus('Loading AI model...', 10);

// Create a text generation pipeline with progress tracking
this.generator = await pipeline(
"text-generation",
"onnx-community/Llama-3.2-1B-Instruct-q4f16",
{
dtype: "q4f16",
device: "webgpu",
progress_callback: (progress) => {
if (progress.status === 'progress') {
const percentage = Math.round((progress.loaded / progress.total) * 100);
this.updateLoadingStatus(
`Downloading model: ${progress.file}`,
percentage,
`${this.formatBytes(progress.loaded)} / ${this.formatBytes(progress.total)}`
);
} else if (progress.status === 'done') {
this.updateLoadingStatus('Model loaded successfully!', 100);
}
}
}
);

// Model loaded successfully
setTimeout(() => {
this.loadingScreen.style.display = 'none';
this.chatInterface.style.display = 'flex';
this.userInput.focus();
}, 500);

} catch (error) {
console.error('Error loading model:', error);
this.updateLoadingStatus('Error loading model. Please refresh the page.', 0);
this.loadingDetails.textContent = error.message;
}
}

updateLoadingStatus(status, progress, details = '') {
this.loadingStatus.textContent = status;
this.progressFill.style.width = `${progress}%`;
this.loadingDetails.textContent = details;
}

formatBytes(bytes) {
if (bytes === 0) return '0 Bytes';
const k = 1024;
const sizes = ['Bytes', 'KB', 'MB', 'GB'];
const i = Math.floor(Math.log(bytes) / Math.log(k));
return Math.round(bytes / Math.pow(k, i) * 100) / 100 + ' ' + sizes[i];
}

updateCharCount() {
const count = this.userInput.value.length;
this.charCount.textContent = `${count}/500`;
}

autoResizeTextarea() {
this.userInput.style.height = 'auto';
this.userInput.style.height = Math.min(this.userInput.scrollHeight, 120) + 'px';
}

updateSendButton() {
const hasText = this.userInput.value.trim().length > 0;
this.sendBtn.disabled = !hasText || this.isGenerating;
}

async handleSend() {
const message = this.userInput.value.trim();
if (!message || this.isGenerating) return;

// Add user message
this.addMessage(message, 'user');
this.messages.push({ role: "user", content: message });

// Clear input
this.userInput.value = '';
this.updateCharCount();
this.updateSendButton();
this.userInput.style.height = 'auto';

// Show typing indicator
const typingIndicator = this.addTypingIndicator();
this.isGenerating = true;

try {
// Create AI message container
const aiMessageDiv = this.createMessageElement('', 'ai');
typingIndicator.remove();
this.messagesContainer.appendChild(aiMessageDiv);

const contentDiv = aiMessageDiv.querySelector('.message-content p');
let fullResponse = '';

// Generate response with streaming
const output = await this.generator(this.messages, {
max_new_tokens: 512,
do_sample: false,
temperature: 0.7,
top_p: 0.9,
streamer: new TextStreamer(this.generator.tokenizer, {
skip_prompt: true,
skip_special_tokens: true,
callback_function: (text) => {
fullResponse += text;
contentDiv.textContent = fullResponse;
this.scrollToBottom();
},
}),
});

// Get final response
const finalResponse = output[0].generated_text.at(-1).content;
contentDiv.textContent = finalResponse;

// Add to message history
this.messages.push({ role: "assistant", content: finalResponse });

} catch (error) {
console.error('Error generating response:', error);
typingIndicator.remove();
this.addMessage('Sorry, I encountered an error. Please try again.', 'ai');
} finally {
this.isGenerating = false;
this.updateSendButton();
this.scrollToBottom();
}
}

addMessage(content, role) {
const messageDiv = this.createMessageElement(content, role);

// Remove welcome message if it exists
const welcomeMsg = this.messagesContainer.querySelector('.welcome-message');
if (welcomeMsg) {
welcomeMsg.remove();
}

this.messagesContainer.appendChild(messageDiv);
this.scrollToBottom();
}

createMessageElement(content, role) {
const messageDiv = document.createElement('div');
messageDiv.className = `message ${role}`;

const avatar = document.createElement('div');
avatar.className = 'message-avatar';
avatar.textContent = role === 'user' ? '👤' : '🤖';

const contentDiv = document.createElement('div');
contentDiv.className = 'message-content';

const textP = document.createElement('p');
textP.textContent = content;
contentDiv.appendChild(textP);

messageDiv.appendChild(avatar);
messageDiv.appendChild(contentDiv);

return messageDiv;
}

addTypingIndicator() {
const messageDiv = document.createElement('div');
messageDiv.className = 'message ai';

const avatar = document.createElement('div');
avatar.className = 'message-avatar';
avatar.textContent = '🤖';

const contentDiv = document.createElement('div');
contentDiv.className = 'message-content';

const typingDiv = document.createElement('div');
typingDiv.className = 'typing-indicator';
typingDiv.innerHTML = '<div class="typing-dot"></div>
<div class="typing-dot"></div>
<div class="typing-dot"></div>';

contentDiv.appendChild(typingDiv);
messageDiv.appendChild(avatar);
messageDiv.appendChild(contentDiv);

this.messagesContainer.appendChild(messageDiv);
this.scrollToBottom();

return messageDiv;
}

scrollToBottom() {
this.messagesContainer.scrollTop = this.messagesContainer.scrollHeight;
}
}

// Initialize the app when DOM is ready
document.addEventListener('DOMContentLoaded', () => {
new ChatApp();
});