Hoi,

Org special block names (within Org) appear to be case-insensitive. That
is, I can write either:

#+BEGIN_NOTES
...
#+END_NOTES

or

#+begin_notes
...
#+end_notes

and Org is happy. I think the switch from Org 8 to 9 changed the default
templates to insert lower-case blocks instead of upper case blocks, so it's
natural now to have files that contain a mix of both cases.

This is a problem for HTML export, as they get converted to:

<div class="NOTES">...</div>

or

<div class="notes">...</div>

depending on the original case of the special block in the .org file. HTML
class element values are case sensitive in non-quirks mode browsers, so
this makes existing CSS for content exported by Org fail, as

div.NOTES { ... }

does not match a <div class="notes">.

A quick local fix is:

(defun my/downcase-special-block (ohsb special-block contents info)
  (let ((special-block-copy (org-element-copy special-block)))
    (org-element-put-property
     special-block-copy
     :type
     (downcase (org-element-property :type special-block)))
    (funcall ohsb special-block-copy contents info)))

(advice-add #'org-html-special-block :around
            #'my/downcase-special-block)

But I wanted to raise this in case there was any interest in a more general
solution (perhaps a configuration option to either (a) retain case (current
behaviour), (b) convert to lower case, (c) convert to upper case?

N