From f3aa7c99f092157ccd3182ffeea922240400a568 Mon Sep 17 00:00:00 2001
From: Ravi R Kiran <aine.marina@gmail.com>
Date: Mon, 31 May 2021 21:45:59 -0500
Subject: HTML export with dark background needs css support


diff --git a/lisp/ravi-init-org.el b/lisp/ravi-init-org.el
index 1b008a1..c4c3585 100644
--- a/lisp/ravi-init-org.el
+++ b/lisp/ravi-init-org.el
@@ -90,6 +90,32 @@ When nil, use the default face background.")
     (setq org-modules '(ol-bbdb ol-bookmark ol-git-link ol-info ol-man org-id))
     (setq org-use-speed-commands t)
 
+    ;; Respect theme for code block output if enabled
+    ;; https://emacs.stackexchange.com/questions/3374/set-the-background-of-org-exported-code-blocks-according-to-theme
+    ;; Code above was modified to
+    ;;   - use hexadecimal color values to avoid color names
+    ;;   - modify org-html-head-extra only if colors were not already present; otherwise
+    ;;     we end up appending to it on every export
+    (defvar ravi/org-html-code-block-parameter-set nil
+      "Set foreground and background for code blocks according to theme")
+    (defun ravi/org-inline-css-hook (exporter)
+      "Insert custom inline css to automatically set the
+background of code according to theme"
+      (when (and (eq exporter 'html)
+                 ;; To do: only if htmlize is used
+                 ravi/org-html-code-block-parameter-set)
+        (let* ((converter (lambda (x) (apply #'color-rgb-to-hex
+                                             (flatten-list (list (color-name-to-rgb x) 2)))))
+               (pre-bg (funcall converter (face-background 'default)))
+               (pre-fg (funcall converter (face-foreground 'default)))
+               (extra (format "<style type=\"text/css\">\n pre.src {background-color: %s; color: %s;}</style>\n"
+                              pre-bg pre-fg)))
+          (unless (and org-html-head-extra
+                       (string-match (regexp-quote extra) org-html-head-extra))
+            (set (make-local-variable 'org-html-head-extra)
+                 (concat org-html-head-extra extra))))))
+    (add-hook 'org-export-before-processing-hook 'ravi/org-inline-css-hook)
+
     (defun ravi/org-color-customization ()
       "Color customization for org mode"
       (setq ravi/org-html-code-block-parameter-set t)
-- 
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