Add dark mode support

[WoD STALKER]

Hi !

First of thank you so much for this amazing tool, i wish i had found it sooner ! I wanted to give a small suggestion :  I am a huge lover of dark mode things, as i find white stuff way too bright for my eyes like many others. I usually use a chrome extension to convert normal website into dark websites (darkreader), but sometimes it messes up with the stylesheet too much. I wanted to know if you could implement a native dark mode for WaveDrom (which would also be good for the non web version on which i can't use any extension...) ?

Thank you