Create Theme or Edit Existing Theme

I've purchased Even Bookings extension to day. and would like to edit an existing theme so that colors match my site. I am not a color by any means but I do understand...which is why I am looking at a quick what to edit color values.

I was hoping there would be a color manager inside the extension so that we would not need to edit CCS files

Any help would be appreciated

The EvenBook Demo site has a custom Color Light Green I am looking at doing the same but with this color #37c9da
where do I edit default colors

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