JS for Darkmode or Lightmode to swich different css-styles (theming) + switching in Language

[blackcrack]

Hi,

would nice if at the code a JS for switching to different css Styles in the Document for better see the Text
and code parts, because like it is now, it's the code in lightmode really less contrast .. therefor would it pretty nice to have a better "theme" changing at the head of the document in Java for load a other "theme" for different modes.. therewith would it also able for switching by reading in darkmode.. and able for setting up something like a cookie for set up the configuration of this document..

and by side, load the right Language or jumping to the right language of the whole Document...

if it is possible to use javascript in an pdf-document ? if yes, could be there a bit magic too ;)
best
Blacky