public static String concatStyles( String style1, String style2 ) {
		if( style1 == null )
			return style2;
		if( style2 == null )
			return style1;
		return style1 + "; " + style2;
	}
Concatenates two styles in CSS syntax.

@param style1 first style, or {@code null}
@param style2 second style, or {@code null}
@return concatenation of the two styles separated by a semicolon
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatStylingSupport.java