- '((((class color) (background light)) (:background "#f0f0f0"))
- (((class color) (background dark)) (:background "#303030")))
+ `((((class color) (background light))
+ ,@(and (>= emacs-major-version 27) '(:extend t))
+ :background "#f0f0f0")
+ (((class color) (background dark))
+ ,@(and (>= emacs-major-version 27) '(:extend t))
+ :background "#303030"))