img.fsl-lazy,
iframe.fsl-lazy-iframe {
  opacity: 0;
  transition: opacity 0.35s ease;
}

img.fsl-loaded,
iframe.fsl-loaded {
  opacity: 1;
}

section.fsl-section {
  content-visibility: auto;
  contain-intrinsic-size: auto 500px;
}

section.fsl-section-ready {
  content-visibility: visible;
}