v0.3.42

Tune stylesheets, video directive, print rules

To enhance webpage printing/pdf generation:
* Add video admonition to replace non-function iframes/embed video.
* Add print media queries to tune the styling
* Limit background to media screen.

Also, use width-content css var as a better breakpoint to the mobile
format.

Signed-off-by: Jorge Marques <[email protected]>