Panel arrangement and volume meter

[alcomposer]

• make right most panel width smaller to match left most panel.
• Move volume meter to right, remove the frame, and consider making the corners rounded.

[jpcima]

Move volume meter to right, remove the frame, and consider making the corners rounded.

What about the size of these? reduce them vertically or leave as is?
There are the colors too, I suppose that dark theme needs its own (at least the back).

[alcomposer]

I would think it may be better to have a gradient for the level meter? Only the background would need a different theme colour.

[jpcima]

That's a possibility; still the color stops of the gradient are allowed to be defined by theme.
The current one is also an interpolation between a pair of color stops.

[alcomposer]

While I think themes should be able to change the colour stops of the meter. Both built-in themes in sfizz should have the same colours for meter, so it's consistent. Otherwise a user may get confused when switching between default / dark theme.