The header background colour is customisable in the Header section of the Customiser.
Use the Brand colours section of the Customiser to change the following colours:
- Primary colour (used throughout the templates and for the dividing lines on widget areas)
- Button colour
- Badge colour (used for Featured posts in widgets)
- Link colour
- Visited link colour
Note that the system will automatically use a contrasting colour for text on background colours. For example, if you choose a button colour of dark blue, text and icons will be white on the button; if you choose a header background colour of light pink, text will be black on the header area.