     :base000 "black"
     :base0000 "black"
     :base01 "color-18"
+    :base015 "color-18"
     :base02 "color-19"
     :base03 "brightblack"
     :base04 "color-20"


(defun my/base16-add-extra-colors (colors)
  "Add extra (non 16) colors to the color scheme."
  (let ((base00 (plist-get colors :base00)))

    (-snoc
     colors
     :base005 (my/lighten-hex base00 2)
     :base000 (my/darken-hex base00 2)
     :base0000 (my/darken-hex base00 4))))

     (whitespace-tab                               :foreground base04 :background base04)
     (whitespace-trailing                          :foreground base0A :background base08)

     (leerzeichen                                  :foreground base015)

     ;; Parenthesis matching (built-in)
     (show-paren-match                             :foreground base03 :background base0D)
     (show-paren-mismatch                          :foreground base03 :background base09)
