1.0 Release task: Review theme colours

[akademy]

Do the colours look right?

There was some discussion on switching the dark and light versions. The light header works better in the dark theme...

[akademy]

Had some further thoughts on this.

Think the light mode should stay the same - it has Diamond colours. But the dark mode should change to actually be dark! Here's a revised image. The main bar is actually the same colour as in light.