color-theme sensitive hl-line

init.el

;; (set-face-background hl-line-face "medium purple")
;; fix hl-line color dynamically:
(require 'hexrgb)
(defun my-fix-hl-line-color ()
  "Adjust hl-line color relative to current color theme"
  (interactive)
  (let*
      ((color (face-attribute 'default :background))
       (value (hexrgb-value color))
       (threshold 0.32)
       (scale 0.9)
       (separation 0.06)
       (new-value
        (+ threshold
           (* scale
              (+ (- value threshold)
                 (if (< value threshold) 0.15 (- 0.0)))))))
    (set-face-background
     hl-line-face
     (hexrgb-increment-value color (- new-value value)))
    (message "%S %S" value new-value)))

(add-hook 'after-init-hook 'my-fix-hl-line-color)

(if (package-installed-p 'color-theme) 
  (defadvice color-theme-install-at-point (after fix-hl-line activate)
    (my-fix-hl-line-color)))