Widget areas created using Gridgets are different from standard widget areas created through your theme because you are able to style them. You do this through a specially created widget, called ‘Gridget Styles’, that will apply styles to widget areas. Note that this will only work with widget areas you’ve created, not with the standard widget areas defined by your theme.
From the Customizer Panel, add the Gridget Styles widget.
Edit the styles for the widget area:
Note that some styles won’t register unless you have other widgets with content in your widget area.
When you’ve made your changes and you’re happy for them to go live, click ‘Save and Publish’ at the top of the Customizer Panel.