Custom WhatsApp Interface

I'll modify the interface to implement the functionality you've described using HTML, Tailwind CSS, Express, and EJS. We'll create a simple messaging application where users first see a list of received messages, and when clicked, it opens a chat window.

Let's start by setting up the project structure and implementing the required functionality.

Let's begin with the Express server setup:

// server.js
const express = require('express');
const path = require('path');
const app = express();
const port = 3000;

// Sample data
const messages = [
  { id: 1, sender: 'Alice', content: 'Hey, how are you?', timestamp: '10:30 AM' },
  { id: 2, sender: 'Bob', content: 'Can we meet tomorrow?', timestamp: '11:45 AM' },
  { id: 3, sender: 'Charlie', content: 'Don\'t forget about the project!', timestamp: '2:15 PM' },
];

// Set the view engine to EJS
app.set('view engine', 'ejs');
app.set('views', path.join(__dirname, 'views'));

// Serve static files
app.use(express.static(path.join(__dirname, 'public')));

// Routes
app.get('/', (req, res) => {
  res.render('index', { messages });
});

app.get('/chat/:id', (req, res) => {
  const id = parseInt(req.params.id);
  const message = messages.find(m => m.id === id);
  res.render('chat', { message });
});

app.listen(port, () => {
  console.log(`Server running at http://localhost:${port}`);
});

Now, let's create the EJS templates. First, the main page showing the list of messages:

<!-- views/index.ejs -->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Message List</title>
    <script src="https://cdn.tailwindcss.com"></script>
</head>
<body class="bg-gray-100">
    <div class="container mx-auto p-4">
        <h1 class="text-2xl font-bold mb-4">Received Messages</h1>
        <div class="space-y-2">
            <% messages.forEach(message => { %>
                <a href="/chat/<%= message.id %>" class="block bg-white p-4 rounded shadow hover:shadow-md transition">
                    <div class="flex justify-between items-center">
                        <span class="font-semibold"><%= message.sender %></span>
                        <span class="text-sm text-gray-500"><%= message.timestamp %></span>
                    </div>
                    <p class="text-gray-600 truncate"><%= message.content %></p>
                </a>
            <% }); %>
        </div>
    </div>
</body>
</html>

Next, let's create the chat window template:

<!-- views/chat.ejs -->
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Chat with <%= message.sender %></title>
    <script src="https://cdn.tailwindcss.com"></script>
</head>
<body class="bg-gray-100">
    <div class="container mx-auto p-4">
        <div class="bg-white rounded-lg shadow-md overflow-hidden">
            <div class="bg-blue-500 text-white p-4 flex justify-between items-center">
                <h1 class="text-xl font-semibold"><%= message.sender %></h1>
                <a href="/" class="text-sm hover:underline">Back to Messages</a>
            </div>
            <div id="chatWindow" class="h-96 overflow-y-auto p-4 space-y-4">
                <div class="flex justify-start">
                    <div class="bg-gray-200 rounded-lg p-3 max-w-3/4">
                        <p><%= message.content %></p>
                        <span class="text-xs text-gray-500 mt-1 block"><%= message.timestamp %></span>
                    </div>
                </div>
                <!-- More messages will be added here dynamically -->
            </div>
            <div class="border-t p-4">
                <form id="messageForm" class="flex space-x-2">
                    <input type="text" id="messageInput" placeholder="Type a message..." class="flex-grow p-2 border rounded" required>
                    <button type="submit" class="bg-blue-500 text-white px-4 py-2 rounded hover:bg-blue-600">Send</button>
                </form>
            </div>
        </div>
    </div>
    <script>
        const chatWindow = document.getElementById('chatWindow');
        const messageForm = document.getElementById('messageForm');
        const messageInput = document.getElementById('messageInput');

        messageForm.addEventListener('submit', (e) => {
            e.preventDefault();
            const message = messageInput.value.trim();
            if (message) {
                addMessage(message, 'You');
                messageInput.value = '';
            }
        });

        function addMessage(content, sender) {
            const messageElement = document.createElement('div');
            messageElement.className = `flex ${sender === 'You' ? 'justify-end' : 'justify-start'}`;
            messageElement.innerHTML = `
                <div class="${sender === 'You' ? 'bg-blue-500 text-white' : 'bg-gray-200'} rounded-lg p-3 max-w-3/4">
                    <p>${content}</p>
                    <span class="text-xs ${sender === 'You' ? 'text-blue-100' : 'text-gray-500'} mt-1 block">${new Date().toLocaleTimeString()}</span>
                </div>
            `;
            chatWindow.appendChild(messageElement);
            chatWindow.scrollTop = chatWindow.scrollHeight;
        }
    </script>
</body>
</html>

Now, let's create a simple CSS file to ensure Tailwind CSS works correctly:

/* public/styles.css */
@import 'tailwindcss/base';
@import 'tailwindcss/components';
@import 'tailwindcss/utilities';

To run this application, you'll need to set up your project with the following steps:

Initialize a new Node.js project:
npm init -y
Install the required dependencies:
npm install express ejs
Create the file structure:
project-root/ ├── server.js ├── views/ │ ├── index.ejs │ └── chat.ejs └── public/ └── styles.css
Run the server:
node server.js

This implementation provides a simple messaging interface with the following features:

A main page (/) that displays a list of received messages.
Clicking on a message opens a chat window (/chat/:id) for that specific conversation.
The chat window shows the selected message and allows the user to send new messages (client-side only in this example).
The interface is styled using Tailwind CSS for a clean, modern look.
The application is server-rendered using Express and EJS templates.

To make this a fully functional chat application, you would need to add real-time functionality (e.g., using WebSockets), implement user authentication, and connect it to a database to store and retrieve messages. However, this example provides a solid foundation for the UI and basic interaction you requested.