Search: add dark overlay when search bar is open

[inesdgomes]

Something like this:

@justintemps Could you check if this is something we can do in the DS? Or does it need to be done in Drupal?

I still need to adjust the designs.

[beatrizmartinmartins]

https://www.figma.com/design/TnVsWy6VobbHzZdbHdx3Rb/ILO-Page-Templates?m=auto&node-id=5071%3A68012&t=bKz2npDLYdoALE7O-1

[inesdgomes]

@justintemps Is this something we implement in the DS or in Drupal? See designs from @beatrizmartinmartins here: https://www.figma.com/design/TnVsWy6VobbHzZdbHdx3Rb/ILO-Page-Templates?m=auto&node-id=5071%3A68012&t=bKz2npDLYdoALE7O-1