style.css

```css
body {
    font-family: 'Tajawal', sans-serif;
    background-color: #f5f5f5;
    margin: 0;
    padding: 0;
    line-height: 1.6;
    color: #333;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    color: #2c3e50;
}

.voice-box {
    background: white;
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

textarea {
    width: 100%;
    min-height: 150px;
    padding: 10px;
    margin-bottom: 15px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-family: inherit;
    font-size: 16px;
    resize: vertical;
}

.controls {
    display: flex;
    gap: 10px;
    margin-bottom: 20px;
}

select, button {
    padding: 10px 15px;
    border: none;
    border-radius: 4px;
    font-family: inherit;
    font-size: 16px;
}

select {
    flex: 1;
    background-color: #f8f9fa;
}

button {
    background-color: #3498db;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #2980b9;
}

.audio-container {
    margin-top: 20px;
    display: flex;
    flex-direction: column;
    gap: 15px;
    align-items: center;
}

audio {
    width: 100%;
}

.btn {
    display: inline-block;
    padding: 8px 16px;
    background-color: #2ecc71;
    color: white;
    text-decoration: none;
    border-radius: 4px;
    transition: background-color 0.3s;
}

.btn:hover {
    background-color: #27ae60;
}

@media (max-width: 600px) {
    .controls {
        flex-direction: column;
    }
}
```

You'll also need to create a Python backend (app.py) to handle the API requests, but I'll provide that separately if you need it. The current implementation includes:
1. Updated index.html with Arabic welcome message and link to voice generator
2. New voice.html page with voice generation interface
3. New style.css with responsive design and Arabic font support

The voice generation page features:
- Text input area
- Voice selection dropdown
- Generate button 
- Audio player
- Download option
- Responsive design for mobile devices
- RTL support for Arabic text