The Fill of a geometry refers to the main color and the opacity.

Change a fill color by selecting a preset.

Add a new color by clicking the rainbow plus.

A color selector appears. Input a hex code or drag your cursor to select a color.

Click off to close.

Click the back arrow to re-set to the previous value.

To edit a preset, double click a preset swatch.

A color selector appears. Input a hex code or drag your cursor to select a color.

The new preset replaces the original value and is saved to the current project.

Every time the appearance widget is activated in the project going forward, that new preset will be available.

Opacity controls how transparent a geometry is.

Adjust the value between 0% and 100% in the number slider.