Hi,
You can add css code to custom css on template manager or insert them on the files css with path: root / templates/ ot_yourtemplate/ assets / css /
Add Presets file:
#1 open templateDetails.xml file on template
#2 search tag "schemes" and add example:
<schemes>
<scheme id="preset-1" cssFile="preset-1.css" color="#48DBA2" />
<scheme id="preset-2" cssFile="preset-2.css" color="#F75375" />
<scheme id="preset-3" cssFile="preset-3.css" color="#51B2ED" />
<scheme id="preset-4" cssFile="preset-4.css" color="#FDC400" />
</schemes>
then create a file preset-1.css, preset-2.css, preset-3.css,.... on root / templates/ ot_yourtemplate/ assets / css /