There are a lot of options allowing you to customize your shortcode, there they are: Color Options (border, minus sign, containter background, container text, active background, active text, inactive background, inactive text, hover background, hover text), Optional CSS class, your tabs and content, and which tab is open.

How to access: Click [R] for the Shortcode Editor > Select Accordion Stacked Tabs > Select Options to Customize.

With Modifications