I am afraid the built-in classes and their styles are not applicable to the ResourceHeader and are to be applied to the appointments only as shown in the Setting Styles for Appointments
article where the class is set to the Appointment's CssClass property in the AppointmentDataBound handler.
In order to set the ResourceHeaders' styles you can use an approach similar to the one shown in the Resource Grouping
demo and set custom Classes to the element/elements in your ResourceHeaderTemplate (Panels, divs, etc.). These classes can use some of the styles (background-color and color for instance) of the built in Appointment CssClasses, which will help you the desired matching appearance of Appointments and Header.
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