To change the lightness of the UI:
- Choose Affinity Designer>Preferences.
- Choose Edit>Preferences.
- Click the User Interface label.
- Drag the sliders to set the Background Gray level and/or UI Gamma level.
- Uncheck Use hardware OpenGL if you don't want to take advantage of hardware-accelerated 3D rendering.
- Uncheck Lines in points if you want line widths to be expressed in physical measurement (e.g., mm) instead of typographic points.