added feature to switch to dark/light mode based on user's preferred mode

[shee35]

#23
the webpage currently looks like :

light mode:

dark mode:

Feel free to suggest changes , if any.
:)

[mmaismma]

The issue stated that Cub's Contraption already has a dark mode. You were not meant to add that feature to the webpage. Plus if you read the contributing guidelines (which you always should) you would've known that all changes should be committed in the beta files.

You can toggle dark mode by typing invert on the webpage (just like you activate cheats in many games). On typing invert the function darken() toggles dark in body.classList. I updated the issue with more details on fixing the issue, check it out for more info.