Implement a dark theme #287

It'd be nice if the website can use a dark theme when prefers-color-scheme: dark media matches.

In the meantime, you can use https://csclub.uwaterloo.ca/themer to make your own dark theme ;)

Although this part of the website is kinda experimental and may change later on.

can definitely get started on this! would this feature be available on mobile as well or are we hoping for this to be exclusive to desktop users?

@smhonori both mobile and desktop users. We have a colour palette defined at https://csclub.uwaterloo.ca/themer. LMK if you wanna add more colours to it, or change the color names / anything like that.

There's a way to detect if the user prefers dark mode or light mode, and we can use that theme for them automatically.

Most of the dark colour palette has already been drafted, as summarized in this document: https://docs.google.com/document/d/17bnwDN-EDMVVno9fnBVXXOByR2BQLnjb026nTDBIw54/edit?usp=sharing

More details can also be seen on Figma: https://www.figma.com/file/vu3AIDmN8vLALfwPbtPhO4/CS-Club-Official-Figma?node-id=866%3A512

While we can probably get started on this issue, we may want to consult with Design on (a) how should users switch between light/dark mode, and (b) any final colour palette details that we want to clarify.