[Feature]: Preserve background image

### Describe the improvement

If we want to preserve such large background image in markdown, what parameters are available to choose? 

Thanks.

```html
<div style="background-image: url('https://images.pexels.com/photos/1323550/pexels-photo-1323550.jpeg?cs=srgb&dl=pexels-simon73-1323550.jpg'); width: 100vw; height: 100vh; background-size: cover; background-position: center;"></div>

```