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Your LimeSurvey version: [see right hand bottom of your LimeSurvey admin screen]
Own server or LimeSurvey hosting:
Survey theme/template:
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Hi, I would like to change some font colors in the variations of your excellent template bootswatch. What files shall I edit in my PC to upload later on my server? or is there other way to do this?
I am using your release 6.0.6
TIA

Go to "configuration" --> "themes" --> Choose the theme --> "..." --> "Theme editor" or "theme options".

A lot can already be changed by the theme options. If this is not enough, go to the them editor and extend the theme.

You can also do this on a per survey basis. Have a look at "theme options" in the left hand navigation when you are in a specific survey.

Thank you. I will try that