Adding CSS to DIVs

I can’t thank you enough for Kirki. Saves me a lot of time. I would like to know if it is possible to add CSS to my DIVs through Kirki. If not, please is there a better method than this:

<div class="<?php if($mrc_show_class == 'show'){echo 'myclass';}?>">
...
</div>

Thanks

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