Some ways the colour scheme UI could be improved:

1. Global colour scheme should be labelled as "global colour scheme" not "custom colour scheme".
2. Global colour scheme should not say "choose a colour scheme" when there isn't a choice
3. Global colour scheme should not use the label "selected" next to a colour scheme when there's no way to select any other.
4. Space colour scheme should be clearer in showing what is the default (global) colour scheme, and what is the custom. A colour scheme can either be customised or it can be default, but the UI implies there are more options.

It looks like the interface of both space and global colour scheme pages was designed for a situation where there are more than 2 options to choose from. For colour schemes, there is only default or custom. The interface should reflect this better.

Some other ideas:

1. Make it easy to reset a single colour back to either the global default or the saved value. Put two colour boxes on the right of the colour picker in columns labelled 'Global default' and 'Current value', where clicking on them changes the text box value.
2. Hide the unnecessary top row of colour boxes when editing a colour scheme.