Scoped palettes

Give each tabset its own colour scheme. A dropdown in the tabset header picks a palette (blue, orange, green, purple, surface or raised), stored in the tabset's config through an action, so it is saved with the layout. A palette is just a CSS class that sets a few colour variables (background, soft fill, line, text, accent and focus ring); the tabs and panels inside the tabset read them.

• Fragiola palettes
• DropdownMenu
• TabSet className
• Actions.updateNodeAttributes