I've been using material-theme lately, and I sometimes switch around, but I've found that solarized produces the best exported code block results. To avoid having to remember to switch themes when exporting, I wrote a quick wrapper for org-export to do it for me:
(defun my/with-theme (theme fn &rest args) (let ((current-themes custom-enabled-themes)) (mapcar #'disable-theme custom-enabled-themes) (load-theme theme t) (let ((result (apply fn args))) (mapcar #'disable-theme custom-enabled-themes) (mapcar (lambda (theme) (load-theme theme t)) current-themes) result))) (advice-add #'org-export-to-file :around (apply-partially #'my/with-theme 'solarized-dark)) (advice-add #'org-export-to-buffer :around (apply-partially #'my/with-theme 'solarized-dark))
Voilà, no more bizarrely formatted code block exports from whatever theme I might have loaded at the time :)