ThemeBuilder only allows limited control over a specific set of exposed variables. Although these variables are constantly analyzed and updated, some, such as $base-gradient, cannot be modified through ThemeBuilder and require manual adjustments.
Example of variable that is not currently exposed: $base-gradient
The feature request is to explore the possibility of exposing more variables or providing a UI for selecting Kendo variables, bearing in mind that some Kendo themes may have over 2,000 variables.
So far the following variables were requested explicitly:
1623384: $base-gradient
1630912: