Revamp the color palette of the documentation

[Notenlish]

Revamp the color theme for documentation, both for the light theme and dark theme

I think that the color palette of the documentation should be revamped. While the dark theme was a nice addition, it would be beneficial for the documentation colors to be more visually pleasing and modern. I think that a similiar color theme that the index page of pyga.me could be used. I also think that the light-theme colors shouldn't be just black, green and light green. I think it should be more colorful.