Run the attached app. It adds ""-fx-table-header-border-color: null;" to .table-view which results in the bunch of warnings:

WARNING: com.sun.javafx.css.StyleHelper calculateValue Could not resolve '-fx-base' while resolving lookups for '-fx-border-color' from rule '*.table-view *.filler' in stylesheet jar:file:/D:/JavaFX/repos/embedded-scrum-8.0/artifacts/sdk/rt/lib/jfxrt.jar!/com/sun/javafx/scene/control/skin/caspian/caspian.bss
WARNING: com.sun.javafx.css.StyleHelper calculateValue Could not resolve '-fx-base' while resolving lookups for '-fx-border-color' from rule '*.table-view>*.column-header-background>*.show-hide-columns-button' in stylesheet jar:file:/D:/JavaFX/repos/embedded-scrum-8.0/artifacts/sdk/rt/lib/jfxrt.jar!/com/sun/javafx/scene/control/skin/caspian/caspian.bss
WARNING: com.sun.javafx.css.StyleHelper calculateValue Could not resolve '-fx-base' while resolving lookups for '-fx-border-color' from rule '*.table-view *.column-header' in stylesheet jar:file:/D:/JavaFX/repos/embedded-scrum-8.0/artifacts/sdk/rt/lib/jfxrt.jar!/com/sun/javafx/scene/control/skin/caspian/caspian.bss