4.7 Faces

The :custom-face keyword allows customization of package’s faces. Example:

(use-package eruby-mode
  :custom-face
  (eruby-standard-face ((t (:slant italic)))))

(use-package example
  :custom-face
  (example-1-face ((t (:foreground "LightPink"))))
  (example-2-face ((t (:foreground "LightGreen"))) face-defspec-spec))

(use-package zenburn-theme
  :preface
  (setq my/zenburn-colors-alist
        '((fg . "#DCDCCC") (bg . "#1C1C1C") (cyan . "#93E0E3")))
  :custom-face
  (region ((t (:background ,(alist-get my/zenburn-colors-alist 'cyan)))))
  :config
  (load-theme 'zenburn t))