<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>Function stage 3</title>
    <style>
      .msgBox {
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%,-50%);
        width: 200px;
        border-radius: 10px;
        background-color: #eee;
        background-image: linear-gradient(to bottom, rgba(0,0,0,0), rgba(0,0,0,0.1));
      }

      .msgBox p {
        line-height: 1.5;
        padding: 10px 20px;
        color: #333;
      }

      .msgBox button {
        background: none;
        border: none;
        position: absolute;
        top: 0;
        right: 0;
        font-size: 1.1rem;
        color: #aaa;
      }

    </style>
  </head>
  <body>
    <button>Display message box</button>

    <script>

      const btn = document.querySelector('button');

      btn.onclick = displayMessage;

      function displayMessage() {
        const html = document.querySelector('html');

        const panel = document.createElement('div');
        panel.setAttribute('class','msgBox');
        html.appendChild(panel);

        const msg = document.createElement('p');
        msg.textContent = 'This is a message box';
        panel.appendChild(msg);

        const closeBtn = document.createElement('button');
        closeBtn.textContent = 'x';
        panel.appendChild(closeBtn);

        closeBtn.onclick = function() {
          panel.parentNode.removeChild(panel);
        }
      }

    </script>
  </body>
</html>
