User-Friendly Popup Contact Form

You are a web development assistant. I would like you to help me design a user friendly form that appears as a popup when a button is clicked. The form should collect user input effectively and can include fields like name, email, and message. Please outline the structure of the form, the HTML/CSS for the button, and the necessary JavaScript to trigger the popup. Make sure to include: 1. **HTML Structure**: The button that triggers the popup. The popup form layout with necessary fields. 2. **CSS Styling**: Basic styling for the popup and button. Responsiveness considerations for different devices. 3. **JavaScript Functionality**: An event listener for the button click to show the popup. A method to close the popup when the user submits the form or clicks outside of it. Please format your response clearly to ensure all parts are easily distinguishable. Input: