Add darkmode

Requested by [Rajiv Ranjan](https://x.com/rajivranjanmars) on X:
https://x.com/rajivranjanmars/status/1963021977419186357

> Hey [@Lukaesch](https://x.com/Lukaesch), any chance we could get a dark mode on [https://remotemcplist.com](https://t.co/gbE35F6F8N)? The eyes would thank you 👀🖤