If you want to change the style of the tabs or the accordion panels, you simply select one of the bundled themes that you find in the Tag Groups settings, Front End, Themes and Appearance. More information about creating you own theme is available here.
Tag Groups Premium comes with a few standard themes that you can use to give some shape and color to your tags. You apply a theme by using its class name for the enclosing element – “div class” or “table class”.
The color is applied to the “prepend” and “append” elements.
tag-groups-theme-green tag-groups-theme-blue tag-groups-theme-red tag-groups-theme-orange tag-groups-theme-black tag-groups-theme-darkred tag-groups-theme-midnightblue tag-groups-theme-slategray
This is an example:
Since the tag size is fixed, the maximum font size should not exceed 18px. The cloud looks best if all tag labels have the same height.1
For the Shuffle Box you can use the following class names. The color will also be applied to the buttons.
cm-shuffle-box-theme-default (Slategray) cm-shuffle-box-theme-blue
The HTML of the post snippets that appear under the filter can be customized in the Tag Groups menu Front End -> Dynamic Post Filter.
You can change the select menu with the parameter sumoselect=1 in the shortcode or “Use styling for selector.” in the Gutenberg block, “Advanced Styling” section.
Advanced users with some knowledge of CSS can simply copy the corresponding lines from the file /css/frontend.css, change the class names and modify them to create their own variations. Save your customized styling to your child theme’s style.css file or in the WordPress customizer so that changes won’t be overwritten with the next plugin update.
You can find further hints in this article.