<style>
  /* Contenedor principal */
  .iframe-container {
    position: relative;
    width: 100%;
    height: 100vh;
    overflow: hidden;
    border-bottom: 1px solid #444;
  }

  .iframe-container iframe {
    width: 100%;
    height: 100%;
    border: none;
    border-radius: 8px;
  }

  /* Botón grande */
  #fullscreenBtn {
    position: absolute;
    top: 10px;
    right: 10px;
    z-index: 10;
    background-color: #0f62fe;
    color: white;
    border: none;
    padding: 10px 16px;
    border-radius: 8px;
    cursor: pointer;
    font-size: 14px;
    font-weight: 600;
    transition: 0.3s ease;
  }

  #iframeOverlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: #000;
    z-index: 9999;
    display: none;
  }

  #closeOverlay { position: absolute; top: 15px; right: 20px; background: rgba(255,255,255,0.06); color:#fff; border:none; padding:8px 14px; border-radius:6px; cursor:pointer; }
</style>

<div class="iframe-container">
  <button id="fullscreenBtn">⛶ Ver en grande</button>
  <iframe src="https://deemixweb.com" scrolling="no"></iframe>
</div>

<div id="iframeOverlay">
  <button id="closeOverlay">✖ Cerrar</button>
  <iframe src="https://deemixweb.com" scrolling="no"></iframe>
</div>

<script>
  const fullscreenBtn = document.getElementById('fullscreenBtn');
  const overlay = document.getElementById('iframeOverlay');
  const closeOverlay = document.getElementById('closeOverlay');

  fullscreenBtn.addEventListener('click', () => {
    overlay.style.display = 'block';
    document.body.style.overflow = 'hidden';
  });

  closeOverlay.addEventListener('click', () => {
    overlay.style.display = 'none';
    document.body.style.overflow = '';
  });
</script>