protected void paintTabSeparator( Graphics g, int tabPlacement, int x, int y, int w, int h ) {
		float sepWidth = UIScale.scale( 1f );
		float offset = tabSeparatorsFullHeight ? 0 : UIScale.scale( 5f );

		g.setColor( (tabSeparatorColor != null) ? tabSeparatorColor : contentAreaColor );
		if( tabPlacement == LEFT || tabPlacement == RIGHT ) {
			// paint tab separator at bottom side
			((Graphics2D)g).fill( new Rectangle2D.Float( x + offset, y + h - sepWidth, w - (offset * 2), sepWidth ) );
		} else if( _tabPane.getComponentOrientation().isLeftToRight() ) {
			// paint tab separator at right side
			((Graphics2D)g).fill( new Rectangle2D.Float( x + w - sepWidth, y + offset, sepWidth, h - (offset * 2) ) );
		} else {
			// paint tab separator at left side
			((Graphics2D)g).fill( new Rectangle2D.Float( x, y + offset, sepWidth, h - (offset * 2) ) );
		}
	}
The content border insets are used to create a separator between tabs and content.
If client property JTabbedPane.hasFullBorder is true, then the content border insets
are also used for the border.
flatlaf-jide-oss/src/main/java/com/formdev/flatlaf/jideoss/ui/FlatJideTabbedPaneUI.java