Implement Dark Mode, streamline Appearance options

[bitigchi]

One could say that "Dark Mode" is the new fad. I disagree. Computers were always meant to be used with dark interfaces. I mean, come on, whose idea was that to stare at white bright screens all the time? I get it, with the inception of Macintosh, it was kind of a proof-of-concept, showing that it is not necessary to stare at a monochrome black-on-white screen all the time. It was cool, but we never recovered totally.

Without further ado, below stuff would be cool to have:

1. Get rid of colours section in Appearance. Instead:
   1. Have a toggle for dark/light mode
   2. Have a menu to select accent colours
   3. Have a menu to select selection colour
2. Tone down or get rid of the gradient in panels and window title bars. This looks outdated, and looks horrible with a dark background. Original Be look works better with it (some polish still necessary)
3. Standardise system colours. Like:
   1. Primary/secondary/tertiary label colour (light/dark)
   2. Standardised system colours for the accents and selections (optimised for light/dark)
   3. Standardised light/dark panel colours (active/inactive)
   4. Standardised light/dark menu colours (active/inactive)
   5. Standardised light/dark button colours (active/inactive)
4. Tone down window borders. Currently every other system element seems to have a border, and this adds clutter to the general view. System widgets/views should not necessarily be very plain, but there's gotta be a middle ground. For instance:
   1. Windows 10 look is cool, but too plain and glossy dark. It is obvious that this is the work of a professional design team, but IMO not the Haiku way.
   2. GTK3 widgets are very plain and lacks the basic distinctions required for effective human usage. Just look at the dark mode for Mint for instance, it is just dark.
   3. macOS has the best middle ground in my opinion, without much glaring or being too stale. Colours are accurately chosen, windows do not have clutter in terms of elements, and active/inactive distinction is accurately shown.

Also the default font for Haiku is too light/thin. Font weight should be increased a notch to have a better look.

I am attaching two screenshots with a dark look. One has BE, and the other one has Haiku decorator.

[bitigchi]

BE decorator

[bitigchi]

Haiku decorator